wireguard-linux/arch/x86/include, branch update-toolchain

KVM: x86: Disallow read-only memslots for SEV-ES and SEV-SNP (and TDX)

2024-08-14T16:28:24Z

Disallow read-only memslots for SEV-{ES,SNP} VM types, as KVM can't directly emulate instructions for ES/SNP, and instead the guest must explicitly request emulation. Unless the guest explicitly requests emulation without accessing memory, ES/SNP relies on KVM creating an MMIO SPTE, with the subsequent #NPF being reflected into the guest as a #VC. But for read-only memslots, KVM deliberately doesn't create MMIO SPTEs, because except for ES/SNP, doing so requires setting reserved bits in the SPTE, i.e. the SPTE can't be readable while also generating a #VC on writes. Because KVM never creates MMIO SPTEs and jumps directly to emulation, the guest never gets a #VC. And since KVM simply resumes the guest if ES/SNP guests trigger emulation, KVM effectively puts the vCPU into an infinite #NPF loop if the vCPU attempts to write read-only memory. Disallow read-only memory for all VMs with protected state, i.e. for upcoming TDX VMs as well as ES/SNP VMs. For TDX, it's actually possible to support read-only memory, as TDX uses EPT Violation #VE to reflect the fault into the guest, e.g. KVM could configure read-only SPTEs with RX protections and SUPPRESS_VE=0. But there is no strong use case for supporting read-only memslots on TDX, e.g. the main historical usage is to emulate option ROMs, but TDX disallows executing from shared memory. And if someone comes along with a legitimate, strong use case, the restriction can always be lifted for TDX. Don't bother trying to retroactively apply the restriction to SEV-ES VMs that are created as type KVM_X86_DEFAULT_VM. Read-only memslots can't possibly work for SEV-ES, i.e. disallowing such memslots is really just means reporting an error to userspace instead of silently hanging vCPUs. Trying to deal with the ordering between KVM_SEV_INIT and memslot creation isn't worth the marginal benefit it would provide userspace. Fixes: 26c44aa9e076 ("KVM: SEV: define VM types for SEV and SEV-ES") Fixes: 1dfe571c12cf ("KVM: SEV: Add initial SEV-SNP support") Cc: Peter Gonda Cc: Michael Roth Cc: Vishal Annapurve Cc: Ackerly Tng Signed-off-by: Sean Christopherson Message-ID: <20240809190319.1710470-2-seanjc@google.com> Signed-off-by: Paolo Bonzini

x86/paravirt: Fix incorrect virt spinlock setting on bare metal

2024-08-07T18:04:38Z

The kernel can change spinlock behavior when running as a guest. But this guest-friendly behavior causes performance problems on bare metal. The kernel uses a static key to switch between the two modes. In theory, the static key is enabled by default (run in guest mode) and should be disabled for bare metal (and in some guests that want native behavior or paravirt spinlock). A performance drop is reported when running encode/decode workload and BenchSEE cache sub-workload. Bisect points to commit ce0a1b608bfc ("x86/paravirt: Silence unused native_pv_lock_init() function warning"). When CONFIG_PARAVIRT_SPINLOCKS is disabled the virt_spin_lock_key is incorrectly set to true on bare metal. The qspinlock degenerates to test-and-set spinlock, which decreases the performance on bare metal. Set the default value of virt_spin_lock_key to false. If booting in a VM, enable this key. Later during the VM initialization, if other high-efficient spinlock is preferred (e.g. paravirt-spinlock), or the user wants the native qspinlock (via nopvspin boot commandline), the virt_spin_lock_key is disabled accordingly. This results in the following decision matrix: X86_FEATURE_HYPERVISOR Y Y Y N CONFIG_PARAVIRT_SPINLOCKS Y Y N Y/N PV spinlock Y N N Y/N virt_spin_lock_key N Y/N Y N Fixes: ce0a1b608bfc ("x86/paravirt: Silence unused native_pv_lock_init() function warning") Reported-by: Prem Nath Dey Reported-by: Xiaoping Zhou Suggested-by: Dave Hansen Suggested-by: Qiuxu Zhuo Suggested-by: Nikolay Borisov Signed-off-by: Chen Yu Signed-off-by: Thomas Gleixner Reviewed-by: Nikolay Borisov Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20240806112207.29792-1-yu.c.chen@intel.com

Merge tag 'x86-urgent-2024-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-08-04T15:57:08Z

Pull x86 fixes from Thomas Gleixner: - Prevent a deadlock on cpu_hotplug_lock in the aperf/mperf driver. A recent change in the ACPI code which consolidated code pathes moved the invocation of init_freq_invariance_cppc() to be moved to a CPU hotplug handler. The first invocation on AMD CPUs ends up enabling a static branch which dead locks because the static branch enable tries to acquire cpu_hotplug_lock but that lock is already held write by the hotplug machinery. Use static_branch_enable_cpuslocked() instead and take the hotplug lock read for the Intel code path which is invoked from the architecture code outside of the CPU hotplug operations. - Fix the number of reserved bits in the sev_config structure bit field so that the bitfield does not exceed 64 bit. - Add missing Zen5 model numbers - Fix the alignment assumptions of pti_clone_pgtable() and clone_entry_text() on 32-bit: The code assumes PMD aligned code sections, but on 32-bit the kernel entry text is not PMD aligned. So depending on the code size and location, which is configuration and compiler dependent, entry text can cross a PMD boundary. As the start is not PMD aligned adding PMD size to the start address is larger than the end address which results in partially mapped entry code for user space. That causes endless recursion on the first entry from userspace (usually #PF). Cure this by aligning the start address in the addition so it ends up at the next PMD start address. clone_entry_text() enforces PMD mapping, but on 32-bit the tail might eventually be PTE mapped, which causes a map fail because the PMD for the tail is not a large page mapping. Use PTI_LEVEL_KERNEL_IMAGE for the clone() invocation which resolves to PTE on 32-bit and PMD on 64-bit. - Zero the 8-byte case for get_user() on range check failure on 32-bit The recend consolidation of the 8-byte get_user() case broke the zeroing in the failure case again. Establish it by clearing ECX before the range check and not afterwards as that obvioulsy can't be reached when the range check fails * tag 'x86-urgent-2024-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/uaccess: Zero the 8-byte get_range case on failure on 32-bit x86/mm: Fix pti_clone_entry_text() for i386 x86/mm: Fix pti_clone_pgtable() alignment assumption x86/setup: Parse the builtin command line before merging x86/CPU/AMD: Add models 0x60-0x6f to the Zen5 range x86/sev: Fix __reserved field in sev_config x86/aperfmperf: Fix deadlock on cpu_hotplug_lock

Merge branch 'kvm-fixes' into HEAD

2024-08-02T16:33:43Z

* fix latent bug in how usage of large pages is determined for confidential VMs * fix "underline too short" in docs * eliminate log spam from limited APIC timer periods * disallow pre-faulting of memory before SEV-SNP VMs are initialized * delay clearing and encrypting private memory until it is added to guest page tables * this change also enables another small cleanup: the checks in SNP_LAUNCH_UPDATE that limit it to non-populated, private pages can now be moved in the common kvm_gmem_populate() function

x86/setup: Parse the builtin command line before merging

2024-07-31T19:46:35Z

Commit in Fixes was added as a catch-all for cases where the cmdline is parsed before being merged with the builtin one. And promptly one issue appeared, see Link below. The microcode loader really needs to parse it that early, but the merging happens later. Reshuffling the early boot nightmare^W code to handle that properly would be a painful exercise for another day so do the chicken thing and parse the builtin cmdline too before it has been merged. Fixes: 0c40b1c7a897 ("x86/setup: Warn when option parsing is done too early") Reported-by: Mike Lothian Signed-off-by: Borislav Petkov (AMD) Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/all/20240730152108.GAZqkE5Dfi9AuKllRw@fat_crate.local Link: https://lore.kernel.org/r/20240722152330.GCZp55ck8E_FT4kPnC@fat_crate.local

Merge tag 'for-linus-6.11-rc1a-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2024-07-27T16:58:24Z

Pull xen fixes from Juergen Gross: "Two fixes for issues introduced in this merge window: - fix enhanced debugging in the Xen multicall handling - two patches fixing a boot failure when running as dom0 in PVH mode" * tag 'for-linus-6.11-rc1a-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: x86/xen: fix memblock_reserve() usage on PVH x86/xen: move xen_reserve_extra_memory() xen: fix multicall debug data referencing

KVM: x86: disallow pre-fault for SNP VMs before initialization

2024-07-26T18:46:14Z

KVM_PRE_FAULT_MEMORY for an SNP guest can race with sev_gmem_post_populate() in bad ways. The following sequence for instance can potentially trigger an RMP fault: thread A, sev_gmem_post_populate: called thread B, sev_gmem_prepare: places below 'pfn' in a private state in RMP thread A, sev_gmem_post_populate: *vaddr = kmap_local_pfn(pfn + i); thread A, sev_gmem_post_populate: copy_from_user(vaddr, src + i * PAGE_SIZE, PAGE_SIZE); RMP #PF Fix this by only allowing KVM_PRE_FAULT_MEMORY to run after a guest's initial private memory contents have been finalized via KVM_SEV_SNP_LAUNCH_FINISH. Beyond fixing this issue, it just sort of makes sense to enforce this, since the KVM_PRE_FAULT_MEMORY documentation states: "KVM maps memory as if the vCPU generated a stage-2 read page fault" which sort of implies we should be acting on the same guest state that a vCPU would see post-launch after the initial guest memory is all set up. Co-developed-by: Michael Roth Signed-off-by: Michael Roth Signed-off-by: Paolo Bonzini

x86/xen: fix memblock_reserve() usage on PVH

2024-07-25T11:11:08Z

The current usage of memblock_reserve() in init_pvh_bootparams() is done before the .bss is zeroed, and that used to be fine when memblock_reserved_init_regions implicitly ended up in the .meminit.data section. However after commit 73db3abdca58c memblock_reserved_init_regions ends up in the .bss section, thus breaking it's usage before the .bss is cleared. Move and rename the call to xen_reserve_extra_memory() so it's done in the x86_init.oem.arch_setup hook, which gets executed after the .bss has been zeroed, but before calling e820__memory_setup(). Fixes: 73db3abdca58c ("init/modpost: conditionally check section mismatch to __meminit*") Signed-off-by: Roger Pau Monné Reviewed-by: Juergen Gross Message-ID: <20240725073116.14626-3-roger.pau@citrix.com> Signed-off-by: Juergen Gross

Merge tag 'random-6.11-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

2024-07-24T17:29:50Z

Pull random number generator updates from Jason Donenfeld: "This adds getrandom() support to the vDSO. First, it adds a new kind of mapping to mmap(2), MAP_DROPPABLE, which lets the kernel zero out pages anytime under memory pressure, which enables allocating memory that never gets swapped to disk but also doesn't count as being mlocked. Then, the vDSO implementation of getrandom() is introduced in a generic manner and hooked into random.c. Next, this is implemented on x86. (Also, though it's not ready for this pull, somebody has begun an arm64 implementation already) Finally, two vDSO selftests are added. There are also two housekeeping cleanup commits" * tag 'random-6.11-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: MAINTAINERS: add random.h headers to RNG subsection random: note that RNDGETPOOL was removed in 2.6.9-rc2 selftests/vDSO: add tests for vgetrandom x86: vdso: Wire up getrandom() vDSO implementation random: introduce generic vDSO getrandom() implementation mm: add MAP_DROPPABLE for designating always lazily freeable mappings

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2024-07-20T19:41:03Z

Pull kvm updates from Paolo Bonzini: "ARM: - Initial infrastructure for shadow stage-2 MMUs, as part of nested virtualization enablement - Support for userspace changes to the guest CTR_EL0 value, enabling (in part) migration of VMs between heterogenous hardware - Fixes + improvements to pKVM's FF-A proxy, adding support for v1.1 of the protocol - FPSIMD/SVE support for nested, including merged trap configuration and exception routing - New command-line parameter to control the WFx trap behavior under KVM - Introduce kCFI hardening in the EL2 hypervisor - Fixes + cleanups for handling presence/absence of FEAT_TCRX - Miscellaneous fixes + documentation updates LoongArch: - Add paravirt steal time support - Add support for KVM_DIRTY_LOG_INITIALLY_SET - Add perf kvm-stat support for loongarch RISC-V: - Redirect AMO load/store access fault traps to guest - perf kvm stat support - Use guest files for IMSIC virtualization, when available s390: - Assortment of tiny fixes which are not time critical x86: - Fixes for Xen emulation - Add a global struct to consolidate tracking of host values, e.g. EFER - Add KVM_CAP_X86_APIC_BUS_CYCLES_NS to allow configuring the effective APIC bus frequency, because TDX - Print the name of the APICv/AVIC inhibits in the relevant tracepoint - Clean up KVM's handling of vendor specific emulation to consistently act on "compatible with Intel/AMD", versus checking for a specific vendor - Drop MTRR virtualization, and instead always honor guest PAT on CPUs that support self-snoop - Update to the newfangled Intel CPU FMS infrastructure - Don't advertise IA32_PERF_GLOBAL_OVF_CTRL as an MSR-to-be-saved, as it reads '0' and writes from userspace are ignored - Misc cleanups x86 - MMU: - Small cleanups, renames and refactoring extracted from the upcoming Intel TDX support - Don't allocate kvm_mmu_page.shadowed_translation for shadow pages that can't hold leafs SPTEs - Unconditionally drop mmu_lock when allocating TDP MMU page tables for eager page splitting, to avoid stalling vCPUs when splitting huge pages - Bug the VM instead of simply warning if KVM tries to split a SPTE that is non-present or not-huge. KVM is guaranteed to end up in a broken state because the callers fully expect a valid SPTE, it's all but dangerous to let more MMU changes happen afterwards x86 - AMD: - Make per-CPU save_area allocations NUMA-aware - Force sev_es_host_save_area() to be inlined to avoid calling into an instrumentable function from noinstr code - Base support for running SEV-SNP guests. API-wise, this includes a new KVM_X86_SNP_VM type, encrypting/measure the initial image into guest memory, and finalizing it before launching it. Internally, there are some gmem/mmu hooks needed to prepare gmem-allocated pages before mapping them into guest private memory ranges This includes basic support for attestation guest requests, enough to say that KVM supports the GHCB 2.0 specification There is no support yet for loading into the firmware those signing keys to be used for attestation requests, and therefore no need yet for the host to provide certificate data for those keys. To support fetching certificate data from userspace, a new KVM exit type will be needed to handle fetching the certificate from userspace. An attempt to define a new KVM_EXIT_COCO / KVM_EXIT_COCO_REQ_CERTS exit type to handle this was introduced in v1 of this patchset, but is still being discussed by community, so for now this patchset only implements a stub version of SNP Extended Guest Requests that does not provide certificate data x86 - Intel: - Remove an unnecessary EPT TLB flush when enabling hardware - Fix a series of bugs that cause KVM to fail to detect nested pending posted interrupts as valid wake eents for a vCPU executing HLT in L2 (with HLT-exiting disable by L1) - KVM: x86: Suppress MMIO that is triggered during task switch emulation Explicitly suppress userspace emulated MMIO exits that are triggered when emulating a task switch as KVM doesn't support userspace MMIO during complex (multi-step) emulation Silently ignoring the exit request can result in the WARN_ON_ONCE(vcpu->mmio_needed) firing if KVM exits to userspace for some other reason prior to purging mmio_needed See commit 0dc902267cb3 ("KVM: x86: Suppress pending MMIO write exits if emulator detects exception") for more details on KVM's limitations with respect to emulated MMIO during complex emulator flows Generic: - Rename the AS_UNMOVABLE flag that was introduced for KVM to AS_INACCESSIBLE, because the special casing needed by these pages is not due to just unmovability (and in fact they are only unmovable because the CPU cannot access them) - New ioctl to populate the KVM page tables in advance, which is useful to mitigate KVM page faults during guest boot or after live migration. The code will also be used by TDX, but (probably) not through the ioctl - Enable halt poll shrinking by default, as Intel found it to be a clear win - Setup empty IRQ routing when creating a VM to avoid having to synchronize SRCU when creating a split IRQCHIP on x86 - Rework the sched_in/out() paths to replace kvm_arch_sched_in() with a flag that arch code can use for hooking both sched_in() and sched_out() - Take the vCPU @id as an "unsigned long" instead of "u32" to avoid truncating a bogus value from userspace, e.g. to help userspace detect bugs - Mark a vCPU as preempted if and only if it's scheduled out while in the KVM_RUN loop, e.g. to avoid marking it preempted and thus writing guest memory when retrieving guest state during live migration blackout Selftests: - Remove dead code in the memslot modification stress test - Treat "branch instructions retired" as supported on all AMD Family 17h+ CPUs - Print the guest pseudo-RNG seed only when it changes, to avoid spamming the log for tests that create lots of VMs - Make the PMU counters test less flaky when counting LLC cache misses by doing CLFLUSH{OPT} in every loop iteration" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (227 commits) crypto: ccp: Add the SNP_VLEK_LOAD command KVM: x86/pmu: Add kvm_pmu_call() to simplify static calls of kvm_pmu_ops KVM: x86: Introduce kvm_x86_call() to simplify static calls of kvm_x86_ops KVM: x86: Replace static_call_cond() with static_call() KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST NAE event x86/sev: Move sev_guest.h into common SEV header KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event KVM: x86: Suppress MMIO that is triggered during task switch emulation KVM: x86/mmu: Clean up make_huge_page_split_spte() definition and intro KVM: x86/mmu: Bug the VM if KVM tries to split a !hugepage SPTE KVM: selftests: x86: Add test for KVM_PRE_FAULT_MEMORY KVM: x86: Implement kvm_arch_vcpu_pre_fault_memory() KVM: x86/mmu: Make kvm_mmu_do_page_fault() return mapped level KVM: x86/mmu: Account pf_{fixed,emulate,spurious} in callers of "do page fault" KVM: x86/mmu: Bump pf_taken stat only in the "real" page fault handler KVM: Add KVM_PRE_FAULT_MEMORY vcpu ioctl to pre-populate guest memory KVM: Document KVM_PRE_FAULT_MEMORY ioctl mm, virt: merge AS_UNMOVABLE and AS_INACCESSIBLE perf kvm: Add kvm-stat for loongarch64 LoongArch: KVM: Add PV steal time support in guest side ...