diff options
Diffstat (limited to 'arch/x86/coco/sev/core.c')
| -rw-r--r-- | arch/x86/coco/sev/core.c | 2181 |
1 files changed, 2181 insertions, 0 deletions
diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c new file mode 100644 index 000000000000..b6db4e0b936b --- /dev/null +++ b/arch/x86/coco/sev/core.c @@ -0,0 +1,2181 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * AMD Memory Encryption Support + * + * Copyright (C) 2019 SUSE + * + * Author: Joerg Roedel <jroedel@suse.de> + */ + +#define pr_fmt(fmt) "SEV: " fmt + +#include <linux/sched/debug.h> /* For show_regs() */ +#include <linux/percpu-defs.h> +#include <linux/cc_platform.h> +#include <linux/printk.h> +#include <linux/mm_types.h> +#include <linux/set_memory.h> +#include <linux/memblock.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/cpumask.h> +#include <linux/efi.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/psp-sev.h> +#include <linux/dmi.h> +#include <uapi/linux/sev-guest.h> +#include <crypto/gcm.h> + +#include <asm/init.h> +#include <asm/cpu_entry_area.h> +#include <asm/stacktrace.h> +#include <asm/sev.h> +#include <asm/sev-internal.h> +#include <asm/insn-eval.h> +#include <asm/fpu/xcr.h> +#include <asm/processor.h> +#include <asm/realmode.h> +#include <asm/setup.h> +#include <asm/traps.h> +#include <asm/svm.h> +#include <asm/smp.h> +#include <asm/cpu.h> +#include <asm/apic.h> +#include <asm/cpuid/api.h> +#include <asm/cmdline.h> +#include <asm/msr.h> + +/* AP INIT values as documented in the APM2 section "Processor Initialization State" */ +#define AP_INIT_CS_LIMIT 0xffff +#define AP_INIT_DS_LIMIT 0xffff +#define AP_INIT_LDTR_LIMIT 0xffff +#define AP_INIT_GDTR_LIMIT 0xffff +#define AP_INIT_IDTR_LIMIT 0xffff +#define AP_INIT_TR_LIMIT 0xffff +#define AP_INIT_RFLAGS_DEFAULT 0x2 +#define AP_INIT_DR6_DEFAULT 0xffff0ff0 +#define AP_INIT_GPAT_DEFAULT 0x0007040600070406ULL +#define AP_INIT_XCR0_DEFAULT 0x1 +#define AP_INIT_X87_FTW_DEFAULT 0x5555 +#define AP_INIT_X87_FCW_DEFAULT 0x0040 +#define AP_INIT_CR0_DEFAULT 0x60000010 +#define AP_INIT_MXCSR_DEFAULT 0x1f80 + +static const char * const sev_status_feat_names[] = { + [MSR_AMD64_SEV_ENABLED_BIT] = "SEV", + [MSR_AMD64_SEV_ES_ENABLED_BIT] = "SEV-ES", + [MSR_AMD64_SEV_SNP_ENABLED_BIT] = "SEV-SNP", + [MSR_AMD64_SNP_VTOM_BIT] = "vTom", + [MSR_AMD64_SNP_REFLECT_VC_BIT] = "ReflectVC", + [MSR_AMD64_SNP_RESTRICTED_INJ_BIT] = "RI", + [MSR_AMD64_SNP_ALT_INJ_BIT] = "AI", + [MSR_AMD64_SNP_DEBUG_SWAP_BIT] = "DebugSwap", + [MSR_AMD64_SNP_PREVENT_HOST_IBS_BIT] = "NoHostIBS", + [MSR_AMD64_SNP_BTB_ISOLATION_BIT] = "BTBIsol", + [MSR_AMD64_SNP_VMPL_SSS_BIT] = "VmplSSS", + [MSR_AMD64_SNP_SECURE_TSC_BIT] = "SecureTSC", + [MSR_AMD64_SNP_VMGEXIT_PARAM_BIT] = "VMGExitParam", + [MSR_AMD64_SNP_IBS_VIRT_BIT] = "IBSVirt", + [MSR_AMD64_SNP_VMSA_REG_PROT_BIT] = "VMSARegProt", + [MSR_AMD64_SNP_SMT_PROT_BIT] = "SMTProt", +}; + +/* + * For Secure TSC guests, the BSP fetches TSC_INFO using SNP guest messaging and + * initializes snp_tsc_scale and snp_tsc_offset. These values are replicated + * across the APs VMSA fields (TSC_SCALE and TSC_OFFSET). + */ +static u64 snp_tsc_scale __ro_after_init; +static u64 snp_tsc_offset __ro_after_init; +static u64 snp_tsc_freq_khz __ro_after_init; + +DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); +DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa); + +/* + * SVSM related information: + * When running under an SVSM, the VMPL that Linux is executing at must be + * non-zero. The VMPL is therefore used to indicate the presence of an SVSM. + */ +u8 snp_vmpl __ro_after_init; +EXPORT_SYMBOL_GPL(snp_vmpl); + +static u64 __init get_snp_jump_table_addr(void) +{ + struct snp_secrets_page *secrets; + void __iomem *mem; + u64 addr; + + mem = ioremap_encrypted(sev_secrets_pa, PAGE_SIZE); + if (!mem) { + pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n"); + return 0; + } + + secrets = (__force struct snp_secrets_page *)mem; + + addr = secrets->os_area.ap_jump_table_pa; + iounmap(mem); + + return addr; +} + +static u64 __init get_jump_table_addr(void) +{ + struct ghcb_state state; + unsigned long flags; + struct ghcb *ghcb; + u64 ret = 0; + + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return get_snp_jump_table_addr(); + + local_irq_save(flags); + + ghcb = __sev_get_ghcb(&state); + + vc_ghcb_invalidate(ghcb); + ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_JUMP_TABLE); + ghcb_set_sw_exit_info_1(ghcb, SVM_VMGEXIT_GET_AP_JUMP_TABLE); + ghcb_set_sw_exit_info_2(ghcb, 0); + + sev_es_wr_ghcb_msr(__pa(ghcb)); + VMGEXIT(); + + if (ghcb_sw_exit_info_1_is_valid(ghcb) && + ghcb_sw_exit_info_2_is_valid(ghcb)) + ret = ghcb->save.sw_exit_info_2; + + __sev_put_ghcb(&state); + + local_irq_restore(flags); + + return ret; +} + +static inline void __pval_terminate(u64 pfn, bool action, unsigned int page_size, + int ret, u64 svsm_ret) +{ + WARN(1, "PVALIDATE failure: pfn: 0x%llx, action: %u, size: %u, ret: %d, svsm_ret: 0x%llx\n", + pfn, action, page_size, ret, svsm_ret); + + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); +} + +static void svsm_pval_terminate(struct svsm_pvalidate_call *pc, int ret, u64 svsm_ret) +{ + unsigned int page_size; + bool action; + u64 pfn; + + pfn = pc->entry[pc->cur_index].pfn; + action = pc->entry[pc->cur_index].action; + page_size = pc->entry[pc->cur_index].page_size; + + __pval_terminate(pfn, action, page_size, ret, svsm_ret); +} + +static void pval_pages(struct snp_psc_desc *desc) +{ + struct psc_entry *e; + unsigned long vaddr; + unsigned int size; + unsigned int i; + bool validate; + u64 pfn; + int rc; + + for (i = 0; i <= desc->hdr.end_entry; i++) { + e = &desc->entries[i]; + + pfn = e->gfn; + vaddr = (unsigned long)pfn_to_kaddr(pfn); + size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K; + validate = e->operation == SNP_PAGE_STATE_PRIVATE; + + rc = pvalidate(vaddr, size, validate); + if (!rc) + continue; + + if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) { + unsigned long vaddr_end = vaddr + PMD_SIZE; + + for (; vaddr < vaddr_end; vaddr += PAGE_SIZE, pfn++) { + rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate); + if (rc) + __pval_terminate(pfn, validate, RMP_PG_SIZE_4K, rc, 0); + } + } else { + __pval_terminate(pfn, validate, size, rc, 0); + } + } +} + +static u64 svsm_build_ca_from_pfn_range(u64 pfn, u64 pfn_end, bool action, + struct svsm_pvalidate_call *pc) +{ + struct svsm_pvalidate_entry *pe; + + /* Nothing in the CA yet */ + pc->num_entries = 0; + pc->cur_index = 0; + + pe = &pc->entry[0]; + + while (pfn < pfn_end) { + pe->page_size = RMP_PG_SIZE_4K; + pe->action = action; + pe->ignore_cf = 0; + pe->pfn = pfn; + + pe++; + pfn++; + + pc->num_entries++; + if (pc->num_entries == SVSM_PVALIDATE_MAX_COUNT) + break; + } + + return pfn; +} + +static int svsm_build_ca_from_psc_desc(struct snp_psc_desc *desc, unsigned int desc_entry, + struct svsm_pvalidate_call *pc) +{ + struct svsm_pvalidate_entry *pe; + struct psc_entry *e; + + /* Nothing in the CA yet */ + pc->num_entries = 0; + pc->cur_index = 0; + + pe = &pc->entry[0]; + e = &desc->entries[desc_entry]; + + while (desc_entry <= desc->hdr.end_entry) { + pe->page_size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K; + pe->action = e->operation == SNP_PAGE_STATE_PRIVATE; + pe->ignore_cf = 0; + pe->pfn = e->gfn; + + pe++; + e++; + + desc_entry++; + pc->num_entries++; + if (pc->num_entries == SVSM_PVALIDATE_MAX_COUNT) + break; + } + + return desc_entry; +} + +static void svsm_pval_pages(struct snp_psc_desc *desc) +{ + struct svsm_pvalidate_entry pv_4k[VMGEXIT_PSC_MAX_ENTRY]; + unsigned int i, pv_4k_count = 0; + struct svsm_pvalidate_call *pc; + struct svsm_call call = {}; + unsigned long flags; + bool action; + u64 pc_pa; + int ret; + + /* + * This can be called very early in the boot, use native functions in + * order to avoid paravirt issues. + */ + flags = native_local_irq_save(); + + /* + * The SVSM calling area (CA) can support processing 510 entries at a + * time. Loop through the Page State Change descriptor until the CA is + * full or the last entry in the descriptor is reached, at which time + * the SVSM is invoked. This repeats until all entries in the descriptor + * are processed. + */ + call.caa = svsm_get_caa(); + + pc = (struct svsm_pvalidate_call *)call.caa->svsm_buffer; + pc_pa = svsm_get_caa_pa() + offsetof(struct svsm_ca, svsm_buffer); + + /* Protocol 0, Call ID 1 */ + call.rax = SVSM_CORE_CALL(SVSM_CORE_PVALIDATE); + call.rcx = pc_pa; + + for (i = 0; i <= desc->hdr.end_entry;) { + i = svsm_build_ca_from_psc_desc(desc, i, pc); + + do { + ret = svsm_perform_call_protocol(&call); + if (!ret) + continue; + + /* + * Check if the entry failed because of an RMP mismatch (a + * PVALIDATE at 2M was requested, but the page is mapped in + * the RMP as 4K). + */ + + if (call.rax_out == SVSM_PVALIDATE_FAIL_SIZEMISMATCH && + pc->entry[pc->cur_index].page_size == RMP_PG_SIZE_2M) { + /* Save this entry for post-processing at 4K */ + pv_4k[pv_4k_count++] = pc->entry[pc->cur_index]; + + /* Skip to the next one unless at the end of the list */ + pc->cur_index++; + if (pc->cur_index < pc->num_entries) + ret = -EAGAIN; + else + ret = 0; + } + } while (ret == -EAGAIN); + + if (ret) + svsm_pval_terminate(pc, ret, call.rax_out); + } + + /* Process any entries that failed to be validated at 2M and validate them at 4K */ + for (i = 0; i < pv_4k_count; i++) { + u64 pfn, pfn_end; + + action = pv_4k[i].action; + pfn = pv_4k[i].pfn; + pfn_end = pfn + 512; + + while (pfn < pfn_end) { + pfn = svsm_build_ca_from_pfn_range(pfn, pfn_end, action, pc); + + ret = svsm_perform_call_protocol(&call); + if (ret) + svsm_pval_terminate(pc, ret, call.rax_out); + } + } + + native_local_irq_restore(flags); +} + +static void pvalidate_pages(struct snp_psc_desc *desc) +{ + if (snp_vmpl) + svsm_pval_pages(desc); + else + pval_pages(desc); +} + +static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) +{ + int cur_entry, end_entry, ret = 0; + struct snp_psc_desc *data; + struct es_em_ctxt ctxt; + + vc_ghcb_invalidate(ghcb); + + /* Copy the input desc into GHCB shared buffer */ + data = (struct snp_psc_desc *)ghcb->shared_buffer; + memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc))); + + /* + * As per the GHCB specification, the hypervisor can resume the guest + * before processing all the entries. Check whether all the entries + * are processed. If not, then keep retrying. Note, the hypervisor + * will update the data memory directly to indicate the status, so + * reference the data->hdr everywhere. + * + * The strategy here is to wait for the hypervisor to change the page + * state in the RMP table before guest accesses the memory pages. If the + * page state change was not successful, then later memory access will + * result in a crash. + */ + cur_entry = data->hdr.cur_entry; + end_entry = data->hdr.end_entry; + + while (data->hdr.cur_entry <= data->hdr.end_entry) { + ghcb_set_sw_scratch(ghcb, (u64)__pa(data)); + + /* This will advance the shared buffer data points to. */ + ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0); + + /* + * Page State Change VMGEXIT can pass error code through + * exit_info_2. + */ + if (WARN(ret || ghcb->save.sw_exit_info_2, + "SNP: PSC failed ret=%d exit_info_2=%llx\n", + ret, ghcb->save.sw_exit_info_2)) { + ret = 1; + goto out; + } + + /* Verify that reserved bit is not set */ + if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) { + ret = 1; + goto out; + } + + /* + * Sanity check that entry processing is not going backwards. + * This will happen only if hypervisor is tricking us. + */ + if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry, +"SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n", + end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) { + ret = 1; + goto out; + } + } + +out: + return ret; +} + +static unsigned long __set_pages_state(struct snp_psc_desc *data, unsigned long vaddr, + unsigned long vaddr_end, int op) +{ + struct ghcb_state state; + bool use_large_entry; + struct psc_hdr *hdr; + struct psc_entry *e; + unsigned long flags; + unsigned long pfn; + struct ghcb *ghcb; + int i; + + hdr = &data->hdr; + e = data->entries; + + memset(data, 0, sizeof(*data)); + i = 0; + + while (vaddr < vaddr_end && i < ARRAY_SIZE(data->entries)) { + hdr->end_entry = i; + + if (is_vmalloc_addr((void *)vaddr)) { + pfn = vmalloc_to_pfn((void *)vaddr); + use_large_entry = false; + } else { + pfn = __pa(vaddr) >> PAGE_SHIFT; + use_large_entry = true; + } + + e->gfn = pfn; + e->operation = op; + + if (use_large_entry && IS_ALIGNED(vaddr, PMD_SIZE) && + (vaddr_end - vaddr) >= PMD_SIZE) { + e->pagesize = RMP_PG_SIZE_2M; + vaddr += PMD_SIZE; + } else { + e->pagesize = RMP_PG_SIZE_4K; + vaddr += PAGE_SIZE; + } + + e++; + i++; + } + + /* Page validation must be rescinded before changing to shared */ + if (op == SNP_PAGE_STATE_SHARED) + pvalidate_pages(data); + + local_irq_save(flags); + + if (sev_cfg.ghcbs_initialized) + ghcb = __sev_get_ghcb(&state); + else + ghcb = boot_ghcb; + + /* Invoke the hypervisor to perform the page state changes */ + if (!ghcb || vmgexit_psc(ghcb, data)) + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); + + if (sev_cfg.ghcbs_initialized) + __sev_put_ghcb(&state); + + local_irq_restore(flags); + + /* Page validation must be performed after changing to private */ + if (op == SNP_PAGE_STATE_PRIVATE) + pvalidate_pages(data); + + return vaddr; +} + +static void set_pages_state(unsigned long vaddr, unsigned long npages, int op) +{ + struct snp_psc_desc desc; + unsigned long vaddr_end; + + /* Use the MSR protocol when a GHCB is not available. */ + if (!boot_ghcb) + return early_set_pages_state(vaddr, __pa(vaddr), npages, op); + + vaddr = vaddr & PAGE_MASK; + vaddr_end = vaddr + (npages << PAGE_SHIFT); + + while (vaddr < vaddr_end) + vaddr = __set_pages_state(&desc, vaddr, vaddr_end, op); +} + +void snp_set_memory_shared(unsigned long vaddr, unsigned long npages) +{ + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + set_pages_state(vaddr, npages, SNP_PAGE_STATE_SHARED); +} + +void snp_set_memory_private(unsigned long vaddr, unsigned long npages) +{ + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); +} + +void snp_accept_memory(phys_addr_t start, phys_addr_t end) +{ + unsigned long vaddr, npages; + + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + vaddr = (unsigned long)__va(start); + npages = (end - start) >> PAGE_SHIFT; + + set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); +} + +static int vmgexit_ap_control(u64 event, struct sev_es_save_area *vmsa, u32 apic_id) +{ + bool create = event != SVM_VMGEXIT_AP_DESTROY; + struct ghcb_state state; + unsigned long flags; + struct ghcb *ghcb; + int ret = 0; + + local_irq_save(flags); + + ghcb = __sev_get_ghcb(&state); + + vc_ghcb_invalidate(ghcb); + + if (create) + ghcb_set_rax(ghcb, vmsa->sev_features); + + ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_CREATION); + ghcb_set_sw_exit_info_1(ghcb, + ((u64)apic_id << 32) | + ((u64)snp_vmpl << 16) | + event); + ghcb_set_sw_exit_info_2(ghcb, __pa(vmsa)); + + sev_es_wr_ghcb_msr(__pa(ghcb)); + VMGEXIT(); + + if (!ghcb_sw_exit_info_1_is_valid(ghcb) || + lower_32_bits(ghcb->save.sw_exit_info_1)) { + pr_err("SNP AP %s error\n", (create ? "CREATE" : "DESTROY")); + ret = -EINVAL; + } + + __sev_put_ghcb(&state); + + local_irq_restore(flags); + + return ret; +} + +static int snp_set_vmsa(void *va, void *caa, int apic_id, bool make_vmsa) +{ + int ret; + + if (snp_vmpl) { + struct svsm_call call = {}; + unsigned long flags; + + local_irq_save(flags); + + call.caa = this_cpu_read(svsm_caa); + call.rcx = __pa(va); + + if (make_vmsa) { + /* Protocol 0, Call ID 2 */ + call.rax = SVSM_CORE_CALL(SVSM_CORE_CREATE_VCPU); + call.rdx = __pa(caa); + call.r8 = apic_id; + } else { + /* Protocol 0, Call ID 3 */ + call.rax = SVSM_CORE_CALL(SVSM_CORE_DELETE_VCPU); + } + + ret = svsm_perform_call_protocol(&call); + + local_irq_restore(flags); + } else { + /* + * If the kernel runs at VMPL0, it can change the VMSA + * bit for a page using the RMPADJUST instruction. + * However, for the instruction to succeed it must + * target the permissions of a lesser privileged (higher + * numbered) VMPL level, so use VMPL1. + */ + u64 attrs = 1; + + if (make_vmsa) + attrs |= RMPADJUST_VMSA_PAGE_BIT; + + ret = rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs); + } + + return ret; +} + +static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa, int apic_id) +{ + int err; + + err = snp_set_vmsa(vmsa, NULL, apic_id, false); + if (err) + pr_err("clear VMSA page failed (%u), leaking page\n", err); + else + free_page((unsigned long)vmsa); +} + +static void set_pte_enc(pte_t *kpte, int level, void *va) +{ + struct pte_enc_desc d = { + .kpte = kpte, + .pte_level = level, + .va = va, + .encrypt = true + }; + + prepare_pte_enc(&d); + set_pte_enc_mask(kpte, d.pfn, d.new_pgprot); +} + +static void unshare_all_memory(void) +{ + unsigned long addr, end, size, ghcb; + struct sev_es_runtime_data *data; + unsigned int npages, level; + bool skipped_addr; + pte_t *pte; + int cpu; + + /* Unshare the direct mapping. */ + addr = PAGE_OFFSET; + end = PAGE_OFFSET + get_max_mapped(); + + while (addr < end) { + pte = lookup_address(addr, &level); + size = page_level_size(level); + npages = size / PAGE_SIZE; + skipped_addr = false; + + if (!pte || !pte_decrypted(*pte) || pte_none(*pte)) { + addr += size; + continue; + } + + /* + * Ensure that all the per-CPU GHCBs are made private at the + * end of the unsharing loop so that the switch to the slower + * MSR protocol happens last. + */ + for_each_possible_cpu(cpu) { + data = per_cpu(runtime_data, cpu); + ghcb = (unsigned long)&data->ghcb_page; + + /* Handle the case of a huge page containing the GHCB page */ + if (addr <= ghcb && ghcb < addr + size) { + skipped_addr = true; + break; + } + } + + if (!skipped_addr) { + set_pte_enc(pte, level, (void *)addr); + snp_set_memory_private(addr, npages); + } + addr += size; + } + + /* Unshare all bss decrypted memory. */ + addr = (unsigned long)__start_bss_decrypted; + end = (unsigned long)__start_bss_decrypted_unused; + npages = (end - addr) >> PAGE_SHIFT; + + for (; addr < end; addr += PAGE_SIZE) { + pte = lookup_address(addr, &level); + if (!pte || !pte_decrypted(*pte) || pte_none(*pte)) + continue; + + set_pte_enc(pte, level, (void *)addr); + } + addr = (unsigned long)__start_bss_decrypted; + snp_set_memory_private(addr, npages); + + __flush_tlb_all(); +} + +/* Stop new private<->shared conversions */ +void snp_kexec_begin(void) +{ + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + if (!IS_ENABLED(CONFIG_KEXEC_CORE)) + return; + + /* + * Crash kernel ends up here with interrupts disabled: can't wait for + * conversions to finish. + * + * If race happened, just report and proceed. + */ + if (!set_memory_enc_stop_conversion()) + pr_warn("Failed to stop shared<->private conversions\n"); +} + +/* + * Shutdown all APs except the one handling kexec/kdump and clearing + * the VMSA tag on AP's VMSA pages as they are not being used as + * VMSA page anymore. + */ +static void shutdown_all_aps(void) +{ + struct sev_es_save_area *vmsa; + int apic_id, this_cpu, cpu; + + this_cpu = get_cpu(); + + /* + * APs are already in HLT loop when enc_kexec_finish() callback + * is invoked. + */ + for_each_present_cpu(cpu) { + vmsa = per_cpu(sev_vmsa, cpu); + + /* + * The BSP or offlined APs do not have guest allocated VMSA + * and there is no need to clear the VMSA tag for this page. + */ + if (!vmsa) + continue; + + /* + * Cannot clear the VMSA tag for the currently running vCPU. + */ + if (this_cpu == cpu) { + unsigned long pa; + struct page *p; + + pa = __pa(vmsa); + /* + * Mark the VMSA page of the running vCPU as offline + * so that is excluded and not touched by makedumpfile + * while generating vmcore during kdump. + */ + p = pfn_to_online_page(pa >> PAGE_SHIFT); + if (p) + __SetPageOffline(p); + continue; + } + + apic_id = cpuid_to_apicid[cpu]; + + /* + * Issue AP destroy to ensure AP gets kicked out of guest mode + * to allow using RMPADJUST to remove the VMSA tag on it's + * VMSA page. + */ + vmgexit_ap_control(SVM_VMGEXIT_AP_DESTROY, vmsa, apic_id); + snp_cleanup_vmsa(vmsa, apic_id); + } + + put_cpu(); +} + +void snp_kexec_finish(void) +{ + struct sev_es_runtime_data *data; + unsigned long size, addr; + unsigned int level, cpu; + struct ghcb *ghcb; + pte_t *pte; + + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + if (!IS_ENABLED(CONFIG_KEXEC_CORE)) + return; + + shutdown_all_aps(); + + unshare_all_memory(); + + /* + * Switch to using the MSR protocol to change per-CPU GHCBs to + * private. All the per-CPU GHCBs have been switched back to private, + * so can't do any more GHCB calls to the hypervisor beyond this point + * until the kexec'ed kernel starts running. + */ + boot_ghcb = NULL; + sev_cfg.ghcbs_initialized = false; + + for_each_possible_cpu(cpu) { + data = per_cpu(runtime_data, cpu); + ghcb = &data->ghcb_page; + pte = lookup_address((unsigned long)ghcb, &level); + size = page_level_size(level); + /* Handle the case of a huge page containing the GHCB page */ + addr = (unsigned long)ghcb & page_level_mask(level); + set_pte_enc(pte, level, (void *)addr); + snp_set_memory_private(addr, (size / PAGE_SIZE)); + } +} + +#define __ATTR_BASE (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK) +#define INIT_CS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) +#define INIT_DS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_WRITE_MASK) + +#define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2) +#define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3) + +static void *snp_alloc_vmsa_page(int cpu) +{ + struct page *p; + + /* + * Allocate VMSA page to work around the SNP erratum where the CPU will + * incorrectly signal an RMP violation #PF if a large page (2MB or 1GB) + * collides with the RMP entry of VMSA page. The recommended workaround + * is to not use a large page. + * + * Allocate an 8k page which is also 8k-aligned. + */ + p = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL_ACCOUNT | __GFP_ZERO, 1); + if (!p) + return NULL; + + split_page(p, 1); + + /* Free the first 4k. This page may be 2M/1G aligned and cannot be used. */ + __free_page(p); + + return page_address(p + 1); +} + +static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip, unsigned int cpu) +{ + struct sev_es_save_area *cur_vmsa, *vmsa; + struct svsm_ca *caa; + u8 sipi_vector; + int ret; + u64 cr4; + + /* + * The hypervisor SNP feature support check has happened earlier, just check + * the AP_CREATION one here. + */ + if (!(sev_hv_features & GHCB_HV_FT_SNP_AP_CREATION)) + return -EOPNOTSUPP; + + /* + * Verify the desired start IP against the known trampoline start IP + * to catch any future new trampolines that may be introduced that + * would require a new protected guest entry point. + */ + if (WARN_ONCE(start_ip != real_mode_header->trampoline_start, + "Unsupported SNP start_ip: %lx\n", start_ip)) + return -EINVAL; + + /* Override start_ip with known protected guest start IP */ + start_ip = real_mode_header->sev_es_trampoline_start; + cur_vmsa = per_cpu(sev_vmsa, cpu); + + /* + * A new VMSA is created each time because there is no guarantee that + * the current VMSA is the kernels or that the vCPU is not running. If + * an attempt was done to use the current VMSA with a running vCPU, a + * #VMEXIT of that vCPU would wipe out all of the settings being done + * here. + */ + vmsa = (struct sev_es_save_area *)snp_alloc_vmsa_page(cpu); + if (!vmsa) + return -ENOMEM; + + /* If an SVSM is present, the SVSM per-CPU CAA will be !NULL */ + caa = per_cpu(svsm_caa, cpu); + + /* CR4 should maintain the MCE value */ + cr4 = native_read_cr4() & X86_CR4_MCE; + + /* Set the CS value based on the start_ip converted to a SIPI vector */ + sipi_vector = (start_ip >> 12); + vmsa->cs.base = sipi_vector << 12; + vmsa->cs.limit = AP_INIT_CS_LIMIT; + vmsa->cs.attrib = INIT_CS_ATTRIBS; + vmsa->cs.selector = sipi_vector << 8; + + /* Set the RIP value based on start_ip */ + vmsa->rip = start_ip & 0xfff; + + /* Set AP INIT defaults as documented in the APM */ + vmsa->ds.limit = AP_INIT_DS_LIMIT; + vmsa->ds.attrib = INIT_DS_ATTRIBS; + vmsa->es = vmsa->ds; + vmsa->fs = vmsa->ds; + vmsa->gs = vmsa->ds; + vmsa->ss = vmsa->ds; + + vmsa->gdtr.limit = AP_INIT_GDTR_LIMIT; + vmsa->ldtr.limit = AP_INIT_LDTR_LIMIT; + vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS; + vmsa->idtr.limit = AP_INIT_IDTR_LIMIT; + vmsa->tr.limit = AP_INIT_TR_LIMIT; + vmsa->tr.attrib = INIT_TR_ATTRIBS; + + vmsa->cr4 = cr4; + vmsa->cr0 = AP_INIT_CR0_DEFAULT; + vmsa->dr7 = DR7_RESET_VALUE; + vmsa->dr6 = AP_INIT_DR6_DEFAULT; + vmsa->rflags = AP_INIT_RFLAGS_DEFAULT; + vmsa->g_pat = AP_INIT_GPAT_DEFAULT; + vmsa->xcr0 = AP_INIT_XCR0_DEFAULT; + vmsa->mxcsr = AP_INIT_MXCSR_DEFAULT; + vmsa->x87_ftw = AP_INIT_X87_FTW_DEFAULT; + vmsa->x87_fcw = AP_INIT_X87_FCW_DEFAULT; + + /* SVME must be set. */ + vmsa->efer = EFER_SVME; + + /* + * Set the SNP-specific fields for this VMSA: + * VMPL level + * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) + */ + vmsa->vmpl = snp_vmpl; + vmsa->sev_features = sev_status >> 2; + + /* Populate AP's TSC scale/offset to get accurate TSC values. */ + if (cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) { + vmsa->tsc_scale = snp_tsc_scale; + vmsa->tsc_offset = snp_tsc_offset; + } + + /* Switch the page over to a VMSA page now that it is initialized */ + ret = snp_set_vmsa(vmsa, caa, apic_id, true); + if (ret) { + pr_err("set VMSA page failed (%u)\n", ret); + free_page((unsigned long)vmsa); + + return -EINVAL; + } + + /* Issue VMGEXIT AP Creation NAE event */ + ret = vmgexit_ap_control(SVM_VMGEXIT_AP_CREATE, vmsa, apic_id); + if (ret) { + snp_cleanup_vmsa(vmsa, apic_id); + vmsa = NULL; + } + + /* Free up any previous VMSA page */ + if (cur_vmsa) + snp_cleanup_vmsa(cur_vmsa, apic_id); + + /* Record the current VMSA page */ + per_cpu(sev_vmsa, cpu) = vmsa; + + return ret; +} + +void __init snp_set_wakeup_secondary_cpu(void) +{ + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + /* + * Always set this override if SNP is enabled. This makes it the + * required method to start APs under SNP. If the hypervisor does + * not support AP creation, then no APs will be started. + */ + apic_update_callback(wakeup_secondary_cpu, wakeup_cpu_via_vmgexit); +} + +int __init sev_es_setup_ap_jump_table(struct real_mode_header *rmh) +{ + u16 startup_cs, startup_ip; + phys_addr_t jump_table_pa; + u64 jump_table_addr; + u16 __iomem *jump_table; + + jump_table_addr = get_jump_table_addr(); + + /* On UP guests there is no jump table so this is not a failure */ + if (!jump_table_addr) + return 0; + + /* Check if AP Jump Table is page-aligned */ + if (jump_table_addr & ~PAGE_MASK) + return -EINVAL; + + jump_table_pa = jump_table_addr & PAGE_MASK; + + startup_cs = (u16)(rmh->trampoline_start >> 4); + startup_ip = (u16)(rmh->sev_es_trampoline_start - + rmh->trampoline_start); + + jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE); + if (!jump_table) + return -EIO; + + writew(startup_ip, &jump_table[0]); + writew(startup_cs, &jump_table[1]); + + iounmap(jump_table); + + return 0; +} + +/* + * This is needed by the OVMF UEFI firmware which will use whatever it finds in + * the GHCB MSR as its GHCB to talk to the hypervisor. So make sure the per-cpu + * runtime GHCBs used by the kernel are also mapped in the EFI page-table. + */ +int __init sev_es_efi_map_ghcbs(pgd_t *pgd) +{ + struct sev_es_runtime_data *data; + unsigned long address, pflags; + int cpu; + u64 pfn; + + if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) + return 0; + + pflags = _PAGE_NX | _PAGE_RW; + + for_each_possible_cpu(cpu) { + data = per_cpu(runtime_data, cpu); + + address = __pa(&data->ghcb_page); + pfn = address >> PAGE_SHIFT; + + if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags)) + return 1; + } + + return 0; +} + +static void snp_register_per_cpu_ghcb(void) +{ + struct sev_es_runtime_data *data; + struct ghcb *ghcb; + + data = this_cpu_read(runtime_data); + ghcb = &data->ghcb_page; + + snp_register_ghcb_early(__pa(ghcb)); +} + +void setup_ghcb(void) +{ + if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) + return; + + /* + * Check whether the runtime #VC exception handler is active. It uses + * the per-CPU GHCB page which is set up by sev_es_init_vc_handling(). + * + * If SNP is active, register the per-CPU GHCB page so that the runtime + * exception handler can use it. + */ + if (initial_vc_handler == (unsigned long)kernel_exc_vmm_communication) { + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + snp_register_per_cpu_ghcb(); + + sev_cfg.ghcbs_initialized = true; + + return; + } + + /* + * Make sure the hypervisor talks a supported protocol. + * This gets called only in the BSP boot phase. + */ + if (!sev_es_negotiate_protocol()) + sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); + + /* + * Clear the boot_ghcb. The first exception comes in before the bss + * section is cleared. + */ + memset(&boot_ghcb_page, 0, PAGE_SIZE); + + /* Alright - Make the boot-ghcb public */ + boot_ghcb = &boot_ghcb_page; + + /* SNP guest requires that GHCB GPA must be registered. */ + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + snp_register_ghcb_early(__pa(&boot_ghcb_page)); +} + +#ifdef CONFIG_HOTPLUG_CPU +static void sev_es_ap_hlt_loop(void) +{ + struct ghcb_state state; + struct ghcb *ghcb; + + ghcb = __sev_get_ghcb(&state); + + while (true) { + vc_ghcb_invalidate(ghcb); + ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_HLT_LOOP); + ghcb_set_sw_exit_info_1(ghcb, 0); + ghcb_set_sw_exit_info_2(ghcb, 0); + + sev_es_wr_ghcb_msr(__pa(ghcb)); + VMGEXIT(); + + /* Wakeup signal? */ + if (ghcb_sw_exit_info_2_is_valid(ghcb) && + ghcb->save.sw_exit_info_2) + break; + } + + __sev_put_ghcb(&state); +} + +/* + * Play_dead handler when running under SEV-ES. This is needed because + * the hypervisor can't deliver an SIPI request to restart the AP. + * Instead the kernel has to issue a VMGEXIT to halt the VCPU until the + * hypervisor wakes it up again. + */ +static void sev_es_play_dead(void) +{ + play_dead_common(); + + /* IRQs now disabled */ + + sev_es_ap_hlt_loop(); + + /* + * If we get here, the VCPU was woken up again. Jump to CPU + * startup code to get it back online. + */ + soft_restart_cpu(); +} +#else /* CONFIG_HOTPLUG_CPU */ +#define sev_es_play_dead native_play_dead +#endif /* CONFIG_HOTPLUG_CPU */ + +#ifdef CONFIG_SMP +static void __init sev_es_setup_play_dead(void) +{ + smp_ops.play_dead = sev_es_play_dead; +} +#else +static inline void sev_es_setup_play_dead(void) { } +#endif + +static void __init alloc_runtime_data(int cpu) +{ + struct sev_es_runtime_data *data; + + data = memblock_alloc_node(sizeof(*data), PAGE_SIZE, cpu_to_node(cpu)); + if (!data) + panic("Can't allocate SEV-ES runtime data"); + + per_cpu(runtime_data, cpu) = data; + + if (snp_vmpl) { + struct svsm_ca *caa; + + /* Allocate the SVSM CA page if an SVSM is present */ + caa = memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE); + + per_cpu(svsm_caa, cpu) = caa; + per_cpu(svsm_caa_pa, cpu) = __pa(caa); + } +} + +static void __init init_ghcb(int cpu) +{ + struct sev_es_runtime_data *data; + int err; + + data = per_cpu(runtime_data, cpu); + + err = early_set_memory_decrypted((unsigned long)&data->ghcb_page, + sizeof(data->ghcb_page)); + if (err) + panic("Can't map GHCBs unencrypted"); + + memset(&data->ghcb_page, 0, sizeof(data->ghcb_page)); + + data->ghcb_active = false; + data->backup_ghcb_active = false; +} + +void __init sev_es_init_vc_handling(void) +{ + int cpu; + + BUILD_BUG_ON(offsetof(struct sev_es_runtime_data, ghcb_page) % PAGE_SIZE); + + if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) + return; + + if (!sev_es_check_cpu_features()) + panic("SEV-ES CPU Features missing"); + + /* + * SNP is supported in v2 of the GHCB spec which mandates support for HV + * features. + */ + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { + sev_hv_features = get_hv_features(); + + if (!(sev_hv_features & GHCB_HV_FT_SNP)) + sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED); + } + + /* Initialize per-cpu GHCB pages */ + for_each_possible_cpu(cpu) { + alloc_runtime_data(cpu); + init_ghcb(cpu); + } + + /* If running under an SVSM, switch to the per-cpu CA */ + if (snp_vmpl) { + struct svsm_call call = {}; + unsigned long flags; + int ret; + + local_irq_save(flags); + + /* + * SVSM_CORE_REMAP_CA call: + * RAX = 0 (Protocol=0, CallID=0) + * RCX = New CA GPA + */ + call.caa = svsm_get_caa(); + call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA); + call.rcx = this_cpu_read(svsm_caa_pa); + ret = svsm_perform_call_protocol(&call); + if (ret) + panic("Can't remap the SVSM CA, ret=%d, rax_out=0x%llx\n", + ret, call.rax_out); + + sev_cfg.use_cas = true; + + local_irq_restore(flags); + } + + sev_es_setup_play_dead(); + + /* Secondary CPUs use the runtime #VC handler */ + initial_vc_handler = (unsigned long)kernel_exc_vmm_communication; +} + +/* + * SEV-SNP guests should only execute dmi_setup() if EFI_CONFIG_TABLES are + * enabled, as the alternative (fallback) logic for DMI probing in the legacy + * ROM region can cause a crash since this region is not pre-validated. + */ +void __init snp_dmi_setup(void) +{ + if (efi_enabled(EFI_CONFIG_TABLES)) + dmi_setup(); +} + +static void dump_cpuid_table(void) +{ + const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); + int i = 0; + + pr_info("count=%d reserved=0x%x reserved2=0x%llx\n", + cpuid_table->count, cpuid_table->__reserved1, cpuid_table->__reserved2); + + for (i = 0; i < SNP_CPUID_COUNT_MAX; i++) { + const struct snp_cpuid_fn *fn = &cpuid_table->fn[i]; + + pr_info("index=%3d fn=0x%08x subfn=0x%08x: eax=0x%08x ebx=0x%08x ecx=0x%08x edx=0x%08x xcr0_in=0x%016llx xss_in=0x%016llx reserved=0x%016llx\n", + i, fn->eax_in, fn->ecx_in, fn->eax, fn->ebx, fn->ecx, + fn->edx, fn->xcr0_in, fn->xss_in, fn->__reserved); + } +} + +/* + * It is useful from an auditing/testing perspective to provide an easy way + * for the guest owner to know that the CPUID table has been initialized as + * expected, but that initialization happens too early in boot to print any + * sort of indicator, and there's not really any other good place to do it, + * so do it here. + * + * If running as an SNP guest, report the current VM privilege level (VMPL). + */ +static int __init report_snp_info(void) +{ + const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); + + if (cpuid_table->count) { + pr_info("Using SNP CPUID table, %d entries present.\n", + cpuid_table->count); + + if (sev_cfg.debug) + dump_cpuid_table(); + } + + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + pr_info("SNP running at VMPL%u.\n", snp_vmpl); + + return 0; +} +arch_initcall(report_snp_info); + +static void update_attest_input(struct svsm_call *call, struct svsm_attest_call *input) +{ + /* If (new) lengths have been returned, propagate them up */ + if (call->rcx_out != call->rcx) + input->manifest_buf.len = call->rcx_out; + + if (call->rdx_out != call->rdx) + input->certificates_buf.len = call->rdx_out; + + if (call->r8_out != call->r8) + input->report_buf.len = call->r8_out; +} + +int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, + struct svsm_attest_call *input) +{ + struct svsm_attest_call *ac; + unsigned long flags; + u64 attest_call_pa; + int ret; + + if (!snp_vmpl) + return -EINVAL; + + local_irq_save(flags); + + call->caa = svsm_get_caa(); + + ac = (struct svsm_attest_call *)call->caa->svsm_buffer; + attest_call_pa = svsm_get_caa_pa() + offsetof(struct svsm_ca, svsm_buffer); + + *ac = *input; + + /* + * Set input registers for the request and set RDX and R8 to known + * values in order to detect length values being returned in them. + */ + call->rax = call_id; + call->rcx = attest_call_pa; + call->rdx = -1; + call->r8 = -1; + ret = svsm_perform_call_protocol(call); + update_attest_input(call, input); + + local_irq_restore(flags); + + return ret; +} +EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req); + +static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, + struct snp_guest_request_ioctl *rio) +{ + struct ghcb_state state; + struct es_em_ctxt ctxt; + unsigned long flags; + struct ghcb *ghcb; + int ret; + + rio->exitinfo2 = SEV_RET_NO_FW_CALL; + + /* + * __sev_get_ghcb() needs to run with IRQs disabled because it is using + * a per-CPU GHCB. + */ + local_irq_save(flags); + + ghcb = __sev_get_ghcb(&state); + if (!ghcb) { + ret = -EIO; + goto e_restore_irq; + } + + vc_ghcb_invalidate(ghcb); + + if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { + ghcb_set_rax(ghcb, input->data_gpa); + ghcb_set_rbx(ghcb, input->data_npages); + } + + ret = sev_es_ghcb_hv_call(ghcb, &ctxt, req->exit_code, input->req_gpa, input->resp_gpa); + if (ret) + goto e_put; + + rio->exitinfo2 = ghcb->save.sw_exit_info_2; + switch (rio->exitinfo2) { + case 0: + break; + + case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_BUSY): + ret = -EAGAIN; + break; + + case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN): + /* Number of expected pages are returned in RBX */ + if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { + input->data_npages = ghcb_get_rbx(ghcb); + ret = -ENOSPC; + break; + } + fallthrough; + default: + ret = -EIO; + break; + } + +e_put: + __sev_put_ghcb(&state); +e_restore_irq: + local_irq_restore(flags); + + return ret; +} + +/** + * snp_svsm_vtpm_probe() - Probe if SVSM provides a vTPM device + * + * Check that there is SVSM and that it supports at least TPM_SEND_COMMAND + * which is the only request used so far. + * + * Return: true if the platform provides a vTPM SVSM device, false otherwise. + */ +static bool snp_svsm_vtpm_probe(void) +{ + struct svsm_call call = {}; + + /* The vTPM device is available only if a SVSM is present */ + if (!snp_vmpl) + return false; + + call.caa = svsm_get_caa(); + call.rax = SVSM_VTPM_CALL(SVSM_VTPM_QUERY); + + if (svsm_perform_call_protocol(&call)) + return false; + + /* Check platform commands contains TPM_SEND_COMMAND - platform command 8 */ + return call.rcx_out & BIT_ULL(8); +} + +/** + * snp_svsm_vtpm_send_command() - Execute a vTPM operation on SVSM + * @buffer: A buffer used to both send the command and receive the response. + * + * Execute a SVSM_VTPM_CMD call as defined by + * "Secure VM Service Module for SEV-SNP Guests" Publication # 58019 Revision: 1.00 + * + * All command request/response buffers have a common structure as specified by + * the following table: + * Byte Size In/Out Description + * Offset (Bytes) + * 0x000 4 In Platform command + * Out Platform command response size + * + * Each command can build upon this common request/response structure to create + * a structure specific to the command. See include/linux/tpm_svsm.h for more + * details. + * + * Return: 0 on success, -errno on failure + */ +int snp_svsm_vtpm_send_command(u8 *buffer) +{ + struct svsm_call call = {}; + + call.caa = svsm_get_caa(); + call.rax = SVSM_VTPM_CALL(SVSM_VTPM_CMD); + call.rcx = __pa(buffer); + + return svsm_perform_call_protocol(&call); +} +EXPORT_SYMBOL_GPL(snp_svsm_vtpm_send_command); + +static struct platform_device sev_guest_device = { + .name = "sev-guest", + .id = -1, +}; + +static struct platform_device tpm_svsm_device = { + .name = "tpm-svsm", + .id = -1, +}; + +static int __init snp_init_platform_device(void) +{ + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return -ENODEV; + + if (platform_device_register(&sev_guest_device)) + return -ENODEV; + + if (snp_svsm_vtpm_probe() && + platform_device_register(&tpm_svsm_device)) + return -ENODEV; + + pr_info("SNP guest platform devices initialized.\n"); + return 0; +} +device_initcall(snp_init_platform_device); + +void sev_show_status(void) +{ + int i; + + pr_info("Status: "); + for (i = 0; i < MSR_AMD64_SNP_RESV_BIT; i++) { + if (sev_status & BIT_ULL(i)) { + if (!sev_status_feat_names[i]) + continue; + + pr_cont("%s ", sev_status_feat_names[i]); + } + } + pr_cont("\n"); +} + +void __init snp_update_svsm_ca(void) +{ + if (!snp_vmpl) + return; + + /* Update the CAA to a proper kernel address */ + boot_svsm_caa = &boot_svsm_ca_page; +} + +#ifdef CONFIG_SYSFS +static ssize_t vmpl_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", snp_vmpl); +} + +static struct kobj_attribute vmpl_attr = __ATTR_RO(vmpl); + +static struct attribute *vmpl_attrs[] = { + &vmpl_attr.attr, + NULL +}; + +static struct attribute_group sev_attr_group = { + .attrs = vmpl_attrs, +}; + +static int __init sev_sysfs_init(void) +{ + struct kobject *sev_kobj; + struct device *dev_root; + int ret; + + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return -ENODEV; + + dev_root = bus_get_dev_root(&cpu_subsys); + if (!dev_root) + return -ENODEV; + + sev_kobj = kobject_create_and_add("sev", &dev_root->kobj); + put_device(dev_root); + + if (!sev_kobj) + return -ENOMEM; + + ret = sysfs_create_group(sev_kobj, &sev_attr_group); + if (ret) + kobject_put(sev_kobj); + + return ret; +} +arch_initcall(sev_sysfs_init); +#endif // CONFIG_SYSFS + +static void free_shared_pages(void *buf, size_t sz) +{ + unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; + int ret; + + if (!buf) + return; + + ret = set_memory_encrypted((unsigned long)buf, npages); + if (ret) { + WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); + return; + } + + __free_pages(virt_to_page(buf), get_order(sz)); +} + +static void *alloc_shared_pages(size_t sz) +{ + unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; + struct page *page; + int ret; + + page = alloc_pages(GFP_KERNEL_ACCOUNT, get_order(sz)); + if (!page) + return NULL; + + ret = set_memory_decrypted((unsigned long)page_address(page), npages); + if (ret) { + pr_err("failed to mark page shared, ret=%d\n", ret); + __free_pages(page, get_order(sz)); + return NULL; + } + + return page_address(page); +} + +static u8 *get_vmpck(int id, struct snp_secrets_page *secrets, u32 **seqno) +{ + u8 *key = NULL; + + switch (id) { + case 0: + *seqno = &secrets->os_area.msg_seqno_0; + key = secrets->vmpck0; + break; + case 1: + *seqno = &secrets->os_area.msg_seqno_1; + key = secrets->vmpck1; + break; + case 2: + *seqno = &secrets->os_area.msg_seqno_2; + key = secrets->vmpck2; + break; + case 3: + *seqno = &secrets->os_area.msg_seqno_3; + key = secrets->vmpck3; + break; + default: + break; + } + + return key; +} + +static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) +{ + struct aesgcm_ctx *ctx; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return NULL; + + if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { + pr_err("Crypto context initialization failed\n"); + kfree(ctx); + return NULL; + } + + return ctx; +} + +int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) +{ + /* Adjust the default VMPCK key based on the executing VMPL level */ + if (vmpck_id == -1) + vmpck_id = snp_vmpl; + + mdesc->vmpck = get_vmpck(vmpck_id, mdesc->secrets, &mdesc->os_area_msg_seqno); + if (!mdesc->vmpck) { + pr_err("Invalid VMPCK%d communication key\n", vmpck_id); + return -EINVAL; + } + + /* Verify that VMPCK is not zero. */ + if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { + pr_err("Empty VMPCK%d communication key\n", vmpck_id); + return -EINVAL; + } + + mdesc->vmpck_id = vmpck_id; + + mdesc->ctx = snp_init_crypto(mdesc->vmpck, VMPCK_KEY_LEN); + if (!mdesc->ctx) + return -ENOMEM; + + return 0; +} +EXPORT_SYMBOL_GPL(snp_msg_init); + +struct snp_msg_desc *snp_msg_alloc(void) +{ + struct snp_msg_desc *mdesc; + void __iomem *mem; + + BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); + + mdesc = kzalloc(sizeof(struct snp_msg_desc), GFP_KERNEL); + if (!mdesc) + return ERR_PTR(-ENOMEM); + + mem = ioremap_encrypted(sev_secrets_pa, PAGE_SIZE); + if (!mem) + goto e_free_mdesc; + + mdesc->secrets = (__force struct snp_secrets_page *)mem; + + /* Allocate the shared page used for the request and response message. */ + mdesc->request = alloc_shared_pages(sizeof(struct snp_guest_msg)); + if (!mdesc->request) + goto e_unmap; + + mdesc->response = alloc_shared_pages(sizeof(struct snp_guest_msg)); + if (!mdesc->response) + goto e_free_request; + + return mdesc; + +e_free_request: + free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); +e_unmap: + iounmap(mem); +e_free_mdesc: + kfree(mdesc); + + return ERR_PTR(-ENOMEM); +} +EXPORT_SYMBOL_GPL(snp_msg_alloc); + +void snp_msg_free(struct snp_msg_desc *mdesc) +{ + if (!mdesc) + return; + + kfree(mdesc->ctx); + free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); + free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); + iounmap((__force void __iomem *)mdesc->secrets); + + memset(mdesc, 0, sizeof(*mdesc)); + kfree(mdesc); +} +EXPORT_SYMBOL_GPL(snp_msg_free); + +/* Mutex to serialize the shared buffer access and command handling. */ +static DEFINE_MUTEX(snp_cmd_mutex); + +/* + * If an error is received from the host or AMD Secure Processor (ASP) there + * are two options. Either retry the exact same encrypted request or discontinue + * using the VMPCK. + * + * This is because in the current encryption scheme GHCB v2 uses AES-GCM to + * encrypt the requests. The IV for this scheme is the sequence number. GCM + * cannot tolerate IV reuse. + * + * The ASP FW v1.51 only increments the sequence numbers on a successful + * guest<->ASP back and forth and only accepts messages at its exact sequence + * number. + * + * So if the sequence number were to be reused the encryption scheme is + * vulnerable. If the sequence number were incremented for a fresh IV the ASP + * will reject the request. + */ +static void snp_disable_vmpck(struct snp_msg_desc *mdesc) +{ + pr_alert("Disabling VMPCK%d communication key to prevent IV reuse.\n", + mdesc->vmpck_id); + memzero_explicit(mdesc->vmpck, VMPCK_KEY_LEN); + mdesc->vmpck = NULL; +} + +static inline u64 __snp_get_msg_seqno(struct snp_msg_desc *mdesc) +{ + u64 count; + + lockdep_assert_held(&snp_cmd_mutex); + + /* Read the current message sequence counter from secrets pages */ + count = *mdesc->os_area_msg_seqno; + + return count + 1; +} + +/* Return a non-zero on success */ +static u64 snp_get_msg_seqno(struct snp_msg_desc *mdesc) +{ + u64 count = __snp_get_msg_seqno(mdesc); + + /* + * The message sequence counter for the SNP guest request is a 64-bit + * value but the version 2 of GHCB specification defines a 32-bit storage + * for it. If the counter exceeds the 32-bit value then return zero. + * The caller should check the return value, but if the caller happens to + * not check the value and use it, then the firmware treats zero as an + * invalid number and will fail the message request. + */ + if (count >= UINT_MAX) { + pr_err("request message sequence counter overflow\n"); + return 0; + } + + return count; +} + +static void snp_inc_msg_seqno(struct snp_msg_desc *mdesc) +{ + /* + * The counter is also incremented by the PSP, so increment it by 2 + * and save in secrets page. + */ + *mdesc->os_area_msg_seqno += 2; +} + +static int verify_and_dec_payload(struct snp_msg_desc *mdesc, struct snp_guest_req *req) +{ + struct snp_guest_msg *resp_msg = &mdesc->secret_response; + struct snp_guest_msg *req_msg = &mdesc->secret_request; + struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; + struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; + struct aesgcm_ctx *ctx = mdesc->ctx; + u8 iv[GCM_AES_IV_SIZE] = {}; + + pr_debug("response [seqno %lld type %d version %d sz %d]\n", + resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version, + resp_msg_hdr->msg_sz); + + /* Copy response from shared memory to encrypted memory. */ + memcpy(resp_msg, mdesc->response, sizeof(*resp_msg)); + + /* Verify that the sequence counter is incremented by 1 */ + if (unlikely(resp_msg_hdr->msg_seqno != (req_msg_hdr->msg_seqno + 1))) + return -EBADMSG; + + /* Verify response message type and version number. */ + if (resp_msg_hdr->msg_type != (req_msg_hdr->msg_type + 1) || + resp_msg_hdr->msg_version != req_msg_hdr->msg_version) + return -EBADMSG; + + /* + * If the message size is greater than our buffer length then return + * an error. + */ + if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz)) + return -EBADMSG; + + /* Decrypt the payload */ + memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno))); + if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz, + &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag)) + return -EBADMSG; + + return 0; +} + +static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_req *req) +{ + struct snp_guest_msg *msg = &mdesc->secret_request; + struct snp_guest_msg_hdr *hdr = &msg->hdr; + struct aesgcm_ctx *ctx = mdesc->ctx; + u8 iv[GCM_AES_IV_SIZE] = {}; + + memset(msg, 0, sizeof(*msg)); + + hdr->algo = SNP_AEAD_AES_256_GCM; + hdr->hdr_version = MSG_HDR_VER; + hdr->hdr_sz = sizeof(*hdr); + hdr->msg_type = req->msg_type; + hdr->msg_version = req->msg_version; + hdr->msg_seqno = seqno; + hdr->msg_vmpck = req->vmpck_id; + hdr->msg_sz = req->req_sz; + + /* Verify the sequence number is non-zero */ + if (!hdr->msg_seqno) + return -ENOSR; + + pr_debug("request [seqno %lld type %d version %d sz %d]\n", + hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); + + if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload))) + return -EBADMSG; + + memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno))); + aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo, + AAD_LEN, iv, hdr->authtag); + + return 0; +} + +static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, + struct snp_guest_request_ioctl *rio) +{ + unsigned long req_start = jiffies; + unsigned int override_npages = 0; + u64 override_err = 0; + int rc; + +retry_request: + /* + * Call firmware to process the request. In this function the encrypted + * message enters shared memory with the host. So after this call the + * sequence number must be incremented or the VMPCK must be deleted to + * prevent reuse of the IV. + */ + rc = snp_issue_guest_request(req, &req->input, rio); + switch (rc) { + case -ENOSPC: + /* + * If the extended guest request fails due to having too + * small of a certificate data buffer, retry the same + * guest request without the extended data request in + * order to increment the sequence number and thus avoid + * IV reuse. + */ + override_npages = req->input.data_npages; + req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + /* + * Override the error to inform callers the given extended + * request buffer size was too small and give the caller the + * required buffer size. + */ + override_err = SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN); + + /* + * If this call to the firmware succeeds, the sequence number can + * be incremented allowing for continued use of the VMPCK. If + * there is an error reflected in the return value, this value + * is checked further down and the result will be the deletion + * of the VMPCK and the error code being propagated back to the + * user as an ioctl() return code. + */ + goto retry_request; + + /* + * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been + * throttled. Retry in the driver to avoid returning and reusing the + * message sequence number on a different message. + */ + case -EAGAIN: + if (jiffies - req_start > SNP_REQ_MAX_RETRY_DURATION) { + rc = -ETIMEDOUT; + break; + } + schedule_timeout_killable(SNP_REQ_RETRY_DELAY); + goto retry_request; + } + + /* + * Increment the message sequence number. There is no harm in doing + * this now because decryption uses the value stored in the response + * structure and any failure will wipe the VMPCK, preventing further + * use anyway. + */ + snp_inc_msg_seqno(mdesc); + + if (override_err) { + rio->exitinfo2 = override_err; + + /* + * If an extended guest request was issued and the supplied certificate + * buffer was not large enough, a standard guest request was issued to + * prevent IV reuse. If the standard request was successful, return -EIO + * back to the caller as would have originally been returned. + */ + if (!rc && override_err == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) + rc = -EIO; + } + + if (override_npages) + req->input.data_npages = override_npages; + + return rc; +} + +int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, + struct snp_guest_request_ioctl *rio) +{ + u64 seqno; + int rc; + + guard(mutex)(&snp_cmd_mutex); + + /* Check if the VMPCK is not empty */ + if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { + pr_err_ratelimited("VMPCK is disabled\n"); + return -ENOTTY; + } + + /* Get message sequence and verify that its a non-zero */ + seqno = snp_get_msg_seqno(mdesc); + if (!seqno) + return -EIO; + + /* Clear shared memory's response for the host to populate. */ + memset(mdesc->response, 0, sizeof(struct snp_guest_msg)); + + /* Encrypt the userspace provided payload in mdesc->secret_request. */ + rc = enc_payload(mdesc, seqno, req); + if (rc) + return rc; + + /* + * Write the fully encrypted request to the shared unencrypted + * request page. + */ + memcpy(mdesc->request, &mdesc->secret_request, sizeof(mdesc->secret_request)); + + /* Initialize the input address for guest request */ + req->input.req_gpa = __pa(mdesc->request); + req->input.resp_gpa = __pa(mdesc->response); + req->input.data_gpa = req->certs_data ? __pa(req->certs_data) : 0; + + rc = __handle_guest_request(mdesc, req, rio); + if (rc) { + if (rc == -EIO && + rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) + return rc; + + pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n", + rc, rio->exitinfo2); + + snp_disable_vmpck(mdesc); + return rc; + } + + rc = verify_and_dec_payload(mdesc, req); + if (rc) { + pr_alert("Detected unexpected decode failure from ASP. rc: %d\n", rc); + snp_disable_vmpck(mdesc); + return rc; + } + + return 0; +} +EXPORT_SYMBOL_GPL(snp_send_guest_request); + +static int __init snp_get_tsc_info(void) +{ + struct snp_guest_request_ioctl *rio; + struct snp_tsc_info_resp *tsc_resp; + struct snp_tsc_info_req *tsc_req; + struct snp_msg_desc *mdesc; + struct snp_guest_req *req; + int rc = -ENOMEM; + + tsc_req = kzalloc(sizeof(*tsc_req), GFP_KERNEL); + if (!tsc_req) + return rc; + + /* + * The intermediate response buffer is used while decrypting the + * response payload. Make sure that it has enough space to cover + * the authtag. + */ + tsc_resp = kzalloc(sizeof(*tsc_resp) + AUTHTAG_LEN, GFP_KERNEL); + if (!tsc_resp) + goto e_free_tsc_req; + + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) + goto e_free_tsc_resp; + + rio = kzalloc(sizeof(*rio), GFP_KERNEL); + if (!rio) + goto e_free_req; + + mdesc = snp_msg_alloc(); + if (IS_ERR_OR_NULL(mdesc)) + goto e_free_rio; + + rc = snp_msg_init(mdesc, snp_vmpl); + if (rc) + goto e_free_mdesc; + + req->msg_version = MSG_HDR_VER; + req->msg_type = SNP_MSG_TSC_INFO_REQ; + req->vmpck_id = snp_vmpl; + req->req_buf = tsc_req; + req->req_sz = sizeof(*tsc_req); + req->resp_buf = (void *)tsc_resp; + req->resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN; + req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + rc = snp_send_guest_request(mdesc, req, rio); + if (rc) + goto e_request; + + pr_debug("%s: response status 0x%x scale 0x%llx offset 0x%llx factor 0x%x\n", + __func__, tsc_resp->status, tsc_resp->tsc_scale, tsc_resp->tsc_offset, + tsc_resp->tsc_factor); + + if (!tsc_resp->status) { + snp_tsc_scale = tsc_resp->tsc_scale; + snp_tsc_offset = tsc_resp->tsc_offset; + } else { + pr_err("Failed to get TSC info, response status 0x%x\n", tsc_resp->status); + rc = -EIO; + } + +e_request: + /* The response buffer contains sensitive data, explicitly clear it. */ + memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN); +e_free_mdesc: + snp_msg_free(mdesc); +e_free_rio: + kfree(rio); +e_free_req: + kfree(req); + e_free_tsc_resp: + kfree(tsc_resp); +e_free_tsc_req: + kfree(tsc_req); + + return rc; +} + +void __init snp_secure_tsc_prepare(void) +{ + if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) + return; + + if (snp_get_tsc_info()) { + pr_alert("Unable to retrieve Secure TSC info from ASP\n"); + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SECURE_TSC); + } + + pr_debug("SecureTSC enabled"); +} + +static unsigned long securetsc_get_tsc_khz(void) +{ + return snp_tsc_freq_khz; +} + +void __init snp_secure_tsc_init(void) +{ + unsigned long long tsc_freq_mhz; + + if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) + return; + + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); + rdmsrq(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz); + snp_tsc_freq_khz = (unsigned long)(tsc_freq_mhz * 1000); + + x86_platform.calibrate_cpu = securetsc_get_tsc_khz; + x86_platform.calibrate_tsc = securetsc_get_tsc_khz; +} |