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2021-12-08KVM: nSVM: introduce svm->nested.save to cache save area before checksEmanuele Giuseppe Esposito1-0/+23
This is useful in the next patch, to keep a saved copy of vmcb12 registers and pass it around more easily. Instead of blindly copying everything, we just copy EFER, CR0, CR3, CR4, DR6 and DR7 which are needed by the VMRUN checks. If more fields will need to be checked, it will be quite obvious to see that they must be added in struct vmcb_save_area_cached and in nested_copy_vmcb_save_to_cache(). __nested_copy_vmcb_save_to_cache() takes a vmcb_save_area_cached parameter, which is useful in order to save the state to a local variable. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Message-Id: <20211103140527.752797-3-eesposit@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-12-08KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in nested_vmcb_valid_sregsEmanuele Giuseppe Esposito1-22/+13
Inline nested_vmcb_check_cr3_cr4 as it is not called by anyone else. Doing so simplifies next patches. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20211103140527.752797-2-eesposit@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-01nSVM: Check for reserved encodings of TLB_CONTROL in nested VMCBKrish Sadhukhan1-0/+15
According to section "TLB Flush" in APM vol 2, "Support for TLB_CONTROL commands other than the first two, is optional and is indicated by CPUID Fn8000_000A_EDX[FlushByAsid]. All encodings of TLB_CONTROL not defined in the APM are reserved." Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Message-Id: <20210920235134.101970-3-krish.sadhukhan@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-01KVM: x86: nSVM: implement nested TSC scalingMaxim Levitsky1-2/+27
This was tested by booting a nested guest with TSC=1Ghz, observing the clocks, and doing about 100 cycles of migration. Note that qemu patch is needed to support migration because of a new MSR that needs to be placed in the migration state. The patch will be sent to the qemu mailing list soon. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210914154825.104886-14-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30KVM: x86: nSVM: don't copy pause related settingsMaxim Levitsky1-8/+0
According to the SDM, the CPU never modifies these settings. It loads them on VM entry and updates an internal copy instead. Also don't load them from the vmcb12 as we don't expose these features to the nested guest yet. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210914154825.104886-5-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-23KVM: x86: nSVM: don't copy virt_ext from vmcb12Maxim Levitsky1-1/+0
These field correspond to features that we don't expose yet to L2 While currently there are no CVE worthy features in this field, if AMD adds more features to this field, that could allow guest escapes similar to CVE-2021-3653 and CVE-2021-3656. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210914154825.104886-6-mlevitsk@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-22KVM: x86: SVM: call KVM_REQ_GET_NESTED_STATE_PAGES on exit from SMM modeMaxim Levitsky1-3/+6
Currently the KVM_REQ_GET_NESTED_STATE_PAGES on SVM only reloads PDPTRs, and MSR bitmap, with former not really needed for SMM as SMM exit code reloads them again from SMRAM'S CR3, and later happens to work since MSR bitmap isn't modified while in SMM. Still it is better to be consistient with VMX. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210913140954.165665-5-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-07Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-5/+0
Pull KVM updates from Paolo Bonzini: "ARM: - Page ownership tracking between host EL1 and EL2 - Rely on userspace page tables to create large stage-2 mappings - Fix incompatibility between pKVM and kmemleak - Fix the PMU reset state, and improve the performance of the virtual PMU - Move over to the generic KVM entry code - Address PSCI reset issues w.r.t. save/restore - Preliminary rework for the upcoming pKVM fixed feature - A bunch of MM cleanups - a vGIC fix for timer spurious interrupts - Various cleanups s390: - enable interpretation of specification exceptions - fix a vcpu_idx vs vcpu_id mixup x86: - fast (lockless) page fault support for the new MMU - new MMU now the default - increased maximum allowed VCPU count - allow inhibit IRQs on KVM_RUN while debugging guests - let Hyper-V-enabled guests run with virtualized LAPIC as long as they do not enable the Hyper-V "AutoEOI" feature - fixes and optimizations for the toggling of AMD AVIC (virtualized LAPIC) - tuning for the case when two-dimensional paging (EPT/NPT) is disabled - bugfixes and cleanups, especially with respect to vCPU reset and choosing a paging mode based on CR0/CR4/EFER - support for 5-level page table on AMD processors Generic: - MMU notifier invalidation callbacks do not take mmu_lock unless necessary - improved caching of LRU kvm_memory_slot - support for histogram statistics - add statistics for halt polling and remote TLB flush requests" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (210 commits) KVM: Drop unused kvm_dirty_gfn_invalid() KVM: x86: Update vCPU's hv_clock before back to guest when tsc_offset is adjusted KVM: MMU: mark role_regs and role accessors as maybe unused KVM: MIPS: Remove a "set but not used" variable x86/kvm: Don't enable IRQ when IRQ enabled in kvm_wait KVM: stats: Add VM stat for remote tlb flush requests KVM: Remove unnecessary export of kvm_{inc,dec}_notifier_count() KVM: x86/mmu: Move lpage_disallowed_link further "down" in kvm_mmu_page KVM: x86/mmu: Relocate kvm_mmu_page.tdp_mmu_page for better cache locality Revert "KVM: x86: mmu: Add guest physical address check in translate_gpa()" KVM: x86/mmu: Remove unused field mmio_cached in struct kvm_mmu_page kvm: x86: Increase KVM_SOFT_MAX_VCPUS to 710 kvm: x86: Increase MAX_VCPUS to 1024 kvm: x86: Set KVM_MAX_VCPU_ID to 4*KVM_MAX_VCPUS KVM: VMX: avoid running vmx_handle_exit_irqoff in case of emulation KVM: x86/mmu: Don't freak out if pml5_root is NULL on 4-level host KVM: s390: index kvm->arch.idle_mask by vcpu_idx KVM: s390: Enable specification exception interpretation KVM: arm64: Trim guest debug exception handling KVM: SVM: Add 5-level page table support for SVM ...
2021-08-16KVM: nSVM: always intercept VMLOAD/VMSAVE when nested (CVE-2021-3656)Maxim Levitsky1-0/+3
If L1 disables VMLOAD/VMSAVE intercepts, and doesn't enable Virtual VMLOAD/VMSAVE (currently not supported for the nested hypervisor), then VMLOAD/VMSAVE must operate on the L1 physical memory, which is only possible by making L0 intercept these instructions. Failure to do so allowed the nested guest to run VMLOAD/VMSAVE unintercepted, and thus read/write portions of the host physical memory. Fixes: 89c8a4984fc9 ("KVM: SVM: Enable Virtual VMLOAD VMSAVE feature") Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-16KVM: nSVM: avoid picking up unsupported bits from L2 in int_ctl (CVE-2021-3653)Maxim Levitsky1-3/+7
* Invert the mask of bits that we pick from L2 in nested_vmcb02_prepare_control * Invert and explicitly use VIRQ related bits bitmask in svm_clear_vintr This fixes a security issue that allowed a malicious L1 to run L2 with AVIC enabled, which allowed the L2 to exploit the uninitialized and enabled AVIC to read/write the host physical memory at some offsets. Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler") Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-08-02KVM: nSVM: remove useless kvm_clear_*_queuePaolo Bonzini1-5/+0
For an event to be in injected state when nested_svm_vmrun executes, it must have come from exitintinfo when svm_complete_interrupts ran: vcpu_enter_guest static_call(kvm_x86_run) -> svm_vcpu_run svm_complete_interrupts // now the event went from "exitintinfo" to "injected" static_call(kvm_x86_handle_exit) -> handle_exit svm_invoke_exit_handler vmrun_interception nested_svm_vmrun However, no event could have been in exitintinfo before a VMRUN vmexit. The code in svm.c is a bit more permissive than the one in vmx.c: if (is_external_interrupt(svm->vmcb->control.exit_int_info) && exit_code != SVM_EXIT_EXCP_BASE + PF_VECTOR && exit_code != SVM_EXIT_NPF && exit_code != SVM_EXIT_TASK_SWITCH && exit_code != SVM_EXIT_INTR && exit_code != SVM_EXIT_NMI) but in any case, a VMRUN instruction would not even start to execute during an attempted event delivery. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-27KVM: SVM: tweak warning about enabled AVIC on nested entryMaxim Levitsky1-1/+1
It is possible that AVIC was requested to be disabled but not yet disabled, e.g if the nested entry is done right after svm_vcpu_after_set_cpuid. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210713142023.106183-3-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-26KVM: nSVM: Swap the parameter order for svm_copy_vmrun_state()/svm_copy_vmloadsave_state()Vitaly Kuznetsov1-4/+4
Make svm_copy_vmrun_state()/svm_copy_vmloadsave_state() interface match 'memcpy(dest, src)' to avoid any confusion. No functional change intended. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210719090322.625277-1-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-26KVM: nSVM: Rename nested_svm_vmloadsave() to svm_copy_vmloadsave_state()Vitaly Kuznetsov1-1/+1
To match svm_copy_vmrun_state(), rename nested_svm_vmloadsave() to svm_copy_vmloadsave_state(). Opportunistically add missing braces to 'else' branch in vmload_vmsave_interception(). No functional change intended. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210716144104.465269-1-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15KVM: nSVM: Restore nested control upon leaving SMMVitaly Kuznetsov1-2/+2
If the VM was migrated while in SMM, no nested state was saved/restored, and therefore svm_leave_smm has to load both save and control area of the vmcb12. Save area is already loaded from HSAVE area, so now load the control area as well from the vmcb12. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210628104425.391276-6-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15KVM: nSVM: Introduce svm_copy_vmrun_state()Vitaly Kuznetsov1-18/+22
Separate the code setting non-VMLOAD-VMSAVE state from svm_set_nested_state() into its own function. This is going to be re-used from svm_enter_smm()/svm_leave_smm(). Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210628104425.391276-4-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15KVM: nSVM: Check that VM_HSAVE_PA MSR was set before VMRUNVitaly Kuznetsov1-0/+5
APM states that "The address written to the VM_HSAVE_PA MSR, which holds the address of the page used to save the host state on a VMRUN, must point to a hypervisor-owned page. If this check fails, the WRMSR will fail with a #GP(0) exception. Note that a value of 0 is not considered valid for the VM_HSAVE_PA MSR and a VMRUN that is attempted while the HSAVE_PA is 0 will fail with a #GP(0) exception." svm_set_msr() already checks that the supplied address is valid, so only check for '0' is missing. Add it to nested_svm_vmrun(). Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210628104425.391276-3-vkuznets@redhat.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15KVM: SVM: add module param to control the #SMI interceptionMaxim Levitsky1-0/+4
In theory there are no side effects of not intercepting #SMI, because then #SMI becomes transparent to the OS and the KVM. Plus an observation on recent Zen2 CPUs reveals that these CPUs ignore #SMI interception and never deliver #SMI VMexits. This is also useful to test nested KVM to see that L1 handles #SMIs correctly in case when L1 doesn't intercept #SMI. Finally the default remains the same, the SMI are intercepted by default thus this patch doesn't have any effect unless non default module param value is used. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210707125100.677203-4-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: x86: Enhance comments for MMU roles and nested transition trickinessSean Christopherson1-0/+1
Expand the comments for the MMU roles. The interactions with gfn_track PGD reuse in particular are hairy. Regarding PGD reuse, add comments in the nested virtualization flows to call out why kvm_init_mmu() is unconditionally called even when nested TDP is used. Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210622175739.3610207-50-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: x86/mmu: Move nested NPT reserved bit calculation into MMU properSean Christopherson1-1/+0
Move nested NPT's invocation of reset_shadow_zero_bits_mask() into the MMU proper and unexport said function. Aside from dropping an export, this is a baby step toward eliminating the call entirely by fixing the shadow_root_level confusion. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210622175739.3610207-19-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: nSVM: Add a comment to document why nNPT uses vmcb01, not vCPU stateSean Christopherson1-0/+6
Add a comment in the nested NPT initialization flow to call out that it intentionally uses vmcb01 instead current vCPU state to get the effective hCR4 and hEFER for L1's NPT context. Note, despite nSVM's efforts to handle the case where vCPU state doesn't reflect L1 state, the MMU may still do the wrong thing due to pulling state from the vCPU instead of the passed in CR0/CR4/EFER values. This will be addressed in future commits. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210622175739.3610207-16-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: x86: Fix sizes used to pass around CR0, CR4, and EFERSean Christopherson1-1/+1
When configuring KVM's MMU, pass CR0 and CR4 as unsigned longs, and EFER as a u64 in various flows (mostly MMU). Passing the params as u32s is functionally ok since all of the affected registers reserve bits 63:32 to zero (enforced by KVM), but it's technically wrong. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210622175739.3610207-15-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: x86: Drop pointless @reset_roots from kvm_init_mmu()Sean Christopherson1-1/+1
Remove the @reset_roots param from kvm_init_mmu(), the one user, kvm_mmu_reset_context() has already unloaded the MMU and thus freed and invalidated all roots. This also happens to be why the reset_roots=true paths doesn't leak roots; they're already invalid. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210609234235.1244004-14-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: x86: Drop skip MMU sync and TLB flush params from "new PGD" helpersSean Christopherson1-1/+1
Drop skip_mmu_sync and skip_tlb_flush from __kvm_mmu_new_pgd() now that all call sites unconditionally skip both the sync and flush. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210609234235.1244004-8-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: nSVM: Move TLB flushing logic (or lack thereof) to dedicated helperSean Christopherson1-9/+29
Introduce nested_svm_transition_tlb_flush() and use it force an MMU sync and TLB flush on nSVM VM-Enter and VM-Exit instead of sneaking the logic into the __kvm_mmu_new_pgd() call sites. Add a partial todo list to document issues that need to be addressed before the unconditional sync and flush can be modified to look more like nVMX's logic. In addition to making nSVM's forced flushing more overt (guess who keeps losing track of it), the new helper brings further convergence between nSVM and nVMX, and also sets the stage for dropping the "skip" params from __kvm_mmu_new_pgd(). Cc: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210609234235.1244004-7-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: x86: avoid loading PDPTRs after migration when possibleMaxim Levitsky1-1/+2
if new KVM_*_SREGS2 ioctls are used, the PDPTRs are a part of the migration state and are correctly restored by those ioctls. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210607090203.133058-9-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: nSVM: refactor the CR3 reload on migrationMaxim Levitsky1-7/+25
Document the actual reason why we need to do it on migration and move the call to svm_set_nested_state to be closer to VMX code. To avoid loading the PDPTRs from possibly not up to date memory map, in nested_svm_load_cr3 after the move, move this code to .get_nested_state_pages. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210607090203.133058-5-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: nSVM: Drop pointless pdptrs_changed() check on nested transitionSean Christopherson1-4/+2
Remove the "PDPTRs unchanged" check to skip PDPTR loading during nested SVM transitions as it's not at all an optimization. Reading guest memory to get the PDPTRs isn't magically cheaper by doing it in pdptrs_changed(), and if the PDPTRs did change, KVM will end up doing the read twice. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210607090203.133058-3-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: nVMX: nSVM: 'nested_run' should count guest-entry attempts that make it to guest codeKrish Sadhukhan1-2/+0
Currently, the 'nested_run' statistic counts all guest-entry attempts, including those that fail during vmentry checks on Intel and during consistency checks on AMD. Convert this statistic to count only those guest-entries that make it past these state checks and make it to guest code. This will tell us the number of guest-entries that actually executed or tried to execute guest code. Signed-off-by: Krish Sadhukhan <Krish.Sadhukhan@oracle.com> Message-Id: <20210609180340.104248-2-krish.sadhukhan@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-07KVM: nSVM: remove a warning about vmcb01 VM exit reasonMaxim Levitsky1-1/+0
While in most cases, when returning to use the VMCB01, the exit reason stored in it will be SVM_EXIT_VMRUN, on first VM exit after a nested migration this field can contain anything since the VM entry did happen before the migration. Remove this warning to avoid the false positive. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210504143936.1644378-3-mlevitsk@redhat.com> Fixes: 9a7de6ecc3ed ("KVM: nSVM: If VMRUN is single-stepped, queue the #DB intercept in nested_svm_vmexit()") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-07KVM: nSVM: always restore the L1's GIF on migrationMaxim Levitsky1-0/+2
While usually the L1's GIF is set while L2 runs, and usually migration nested state is loaded after a vCPU reset which also sets L1's GIF to true, this is not guaranteed. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210504143936.1644378-2-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-03KVM: nSVM: leave the guest mode prior to loading a nested stateMaxim Levitsky1-2/+5
This allows the KVM to load the nested state more than once without warnings. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210503125446.1353307-4-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-03KVM: nSVM: fix few bugs in the vmcb02 caching logicMaxim Levitsky1-0/+11
* Define and use an invalid GPA (all ones) for init value of last and current nested vmcb physical addresses. * Reset the current vmcb12 gpa to the invalid value when leaving the nested mode, similar to what is done on nested vmexit. * Reset the last seen vmcb12 address when disabling the nested SVM, as it relies on vmcb02 fields which are freed at that point. Fixes: 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the nested L2 guest") Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210503125446.1353307-3-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-03KVM: nSVM: fix a typo in svm_leave_nestedMaxim Levitsky1-1/+1
When forcibly leaving the nested mode, we should switch to vmcb01 Fixes: 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the nested L2 guest") Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210503125446.1353307-2-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-22Merge branch 'kvm-sev-cgroup' into HEADPaolo Bonzini1-1/+0
2021-04-21nSVM: Check addresses of MSR and IO permission mapsKrish Sadhukhan1-3/+22
According to section "Canonicalization and Consistency Checks" in APM vol 2, the following guest state is illegal: "The MSR or IOIO intercept tables extend to a physical address that is greater than or equal to the maximum supported physical address." Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Message-Id: <20210412215611.110095-5-krish.sadhukhan@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: x86: pending exceptions must not be blocked by an injected eventMaxim Levitsky1-1/+7
Injected interrupts/nmi should not block a pending exception, but rather be either lost if nested hypervisor doesn't intercept the pending exception (as in stock x86), or be delivered in exitintinfo/IDT_VECTORING_INFO field, as a part of a VMexit that corresponds to the pending exception. The only reason for an exception to be blocked is when nested run is pending (and that can't really happen currently but still worth checking for). Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210401143817.1030695-2-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: nSVM: call nested_svm_load_cr3 on nested state loadMaxim Levitsky1-18/+22
While KVM's MMU should be fully reset by loading of nested CR0/CR3/CR4 by KVM_SET_SREGS, we are not in nested mode yet when we do it and therefore only root_mmu is reset. On regular nested entries we call nested_svm_load_cr3 which both updates the guest's CR3 in the MMU when it is needed, and it also initializes the mmu again which makes it initialize the walk_mmu as well when nested paging is enabled in both host and guest. Since we don't call nested_svm_load_cr3 on nested state load, the walk_mmu can be left uninitialized, which can lead to a NULL pointer dereference while accessing it if we happen to get a nested page fault right after entering the nested guest first time after the migration and we decide to emulate it, which leads to the emulator trying to access walk_mmu->gva_to_gpa which is NULL. Therefore we should call this function on nested state load as well. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210401141814.1029036-3-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: x86: Account a variety of miscellaneous allocationsSean Christopherson1-2/+2
Switch to GFP_KERNEL_ACCOUNT for a handful of allocations that are clearly associated with a single task/VM. Note, there are a several SEV allocations that aren't accounted, but those can (hopefully) be fixed by using the local stack for memory. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210331023025.2485960-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: nSVM: If VMRUN is single-stepped, queue the #DB intercept in nested_svm_vmexit()Krish Sadhukhan1-0/+10
According to APM, the #DB intercept for a single-stepped VMRUN must happen after the completion of that instruction, when the guest does #VMEXIT to the host. However, in the current implementation of KVM, the #DB intercept for a single-stepped VMRUN happens after the completion of the instruction that follows the VMRUN instruction. When the #DB intercept handler is invoked, it shows the RIP of the instruction that follows VMRUN, instead of of VMRUN itself. This is an incorrect RIP as far as single-stepping VMRUN is concerned. This patch fixes the problem by checking, in nested_svm_vmexit(), for the condition that the VMRUN instruction is being single-stepped and if so, queues the pending #DB intercept so that the #DB is accounted for before we execute L1's next instruction. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oraacle.com> Message-Id: <20210323175006.73249-2-krish.sadhukhan@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-01Merge branch 'kvm-fix-svm-races' into HEADPaolo Bonzini1-12/+20
2021-04-01Merge branch 'kvm-fix-svm-races' into kvm-masterPaolo Bonzini1-5/+23
2021-04-01KVM: SVM: ensure that EFER.SVME is set when running nested guest or on nested vmexitPaolo Bonzini1-1/+17
Fixing nested_vmcb_check_save to avoid all TOC/TOU races is a bit harder in released kernels, so do the bare minimum by avoiding that EFER.SVME is cleared. This is problematic because svm_set_efer frees the data structures for nested virtualization if EFER.SVME is cleared. Also check that EFER.SVME remains set after a nested vmexit; clearing it could happen if the bit is zero in the save area that is passed to KVM_SET_NESTED_STATE (the save area of the nested state corresponds to the nested hypervisor's state and is restored on the next nested vmexit). Cc: stable@vger.kernel.org Fixes: 2fcf4876ada ("KVM: nSVM: implement on demand allocation of the nested state") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-01KVM: SVM: load control fields from VMCB12 before checking themPaolo Bonzini1-4/+6
Avoid races between check and use of the nested VMCB controls. This for example ensures that the VMRUN intercept is always reflected to the nested hypervisor, instead of being processed by the host. Without this patch, it is possible to end up with svm->nested.hsave pointing to the MSR permission bitmap for nested guests. This bug is CVE-2021-29657. Reported-by: Felix Wilhelm <fwilhelm@google.com> Cc: stable@vger.kernel.org Fixes: 2fcf4876ada ("KVM: nSVM: implement on demand allocation of the nested state") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-15KVM: nSVM: Optimize vmcb12 to vmcb02 save area copiesCathy Avery1-13/+28
Use the vmcb12 control clean field to determine which vmcb12.save registers were marked dirty in order to minimize register copies when switching from L1 to L2. Those vmcb12 registers marked as dirty need to be copied to L0's vmcb02 as they will be used to update the vmcb state cache for the L2 VMRUN. In the case where we have a different vmcb12 from the last L2 VMRUN all vmcb12.save registers must be copied over to L2.save. Tested: kvm-unit-tests kvm selftests Fedora L1 L2 Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Cathy Avery <cavery@redhat.com> Message-Id: <20210301200844.2000-1-cavery@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-15KVM: SVM: Add support for Virtual SPEC_CTRLBabu Moger1-0/+15
Newer AMD processors have a feature to virtualize the use of the SPEC_CTRL MSR. Presence of this feature is indicated via CPUID function 0x8000000A_EDX[20]: GuestSpecCtrl. Hypervisors are not required to enable this feature since it is automatically enabled on processors that support it. A hypervisor may wish to impose speculation controls on guest execution or a guest may want to impose its own speculation controls. Therefore, the processor implements both host and guest versions of SPEC_CTRL. When in host mode, the host SPEC_CTRL value is in effect and writes update only the host version of SPEC_CTRL. On a VMRUN, the processor loads the guest version of SPEC_CTRL from the VMCB. When the guest writes SPEC_CTRL, only the guest version is updated. On a VMEXIT, the guest version is saved into the VMCB and the processor returns to only using the host SPEC_CTRL for speculation control. The guest SPEC_CTRL is located at offset 0x2E0 in the VMCB. The effective SPEC_CTRL setting is the guest SPEC_CTRL setting or'ed with the hypervisor SPEC_CTRL setting. This allows the hypervisor to ensure a minimum SPEC_CTRL if desired. This support also fixes an issue where a guest may sometimes see an inconsistent value for the SPEC_CTRL MSR on processors that support this feature. With the current SPEC_CTRL support, the first write to SPEC_CTRL is intercepted and the virtualized version of the SPEC_CTRL MSR is not updated. When the guest reads back the SPEC_CTRL MSR, it will be 0x0, instead of the actual expected value. There isn’t a security concern here, because the host SPEC_CTRL value is or’ed with the Guest SPEC_CTRL value to generate the effective SPEC_CTRL value. KVM writes with the guest's virtualized SPEC_CTRL value to SPEC_CTRL MSR just before the VMRUN, so it will always have the actual value even though it doesn’t appear that way in the guest. The guest will only see the proper value for the SPEC_CTRL register if the guest was to write to the SPEC_CTRL register again. With Virtual SPEC_CTRL support, the save area spec_ctrl is properly saved and restored. So, the guest will always see the proper value when it is read back. Signed-off-by: Babu Moger <babu.moger@amd.com> Message-Id: <161188100955.28787.11816849358413330720.stgit@bmoger-ubuntu> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-15KVM: nSVM: always use vmcb01 to for vmsave/vmload of guest stateMaxim Levitsky1-3/+0
This allows to avoid copying of these fields between vmcb01 and vmcb02 on nested guest entry/exit. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-15KVM: nSVM: Add helper to synthesize nested VM-Exit without collateralSean Christopherson1-49/+6
Add a helper to consolidate boilerplate for nested VM-Exits that don't provide any data in exit_info_*. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210302174515.2812275-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-15KVM: x86: Handle triple fault in L2 without killing L1Sean Christopherson1-0/+14
Synthesize a nested VM-Exit if L2 triggers an emulated triple fault instead of exiting to userspace, which likely will kill L1. Any flow that does KVM_REQ_TRIPLE_FAULT is suspect, but the most common scenario for L2 killing L1 is if L0 (KVM) intercepts a contributory exception that is _not_intercepted by L1. E.g. if KVM is intercepting #GPs for the VMware backdoor, a #GP that occurs in L2 while vectoring an injected #DF will cause KVM to emulate triple fault. Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Jim Mattson <jmattson@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210302174515.2812275-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-15KVM: SVM: Pass struct kvm_vcpu to exit handlers (and many, many other places)Paolo Bonzini1-63/+65
Refactor the svm_exit_handlers API to pass @vcpu instead of @svm to allow directly invoking common x86 exit handlers (in a future patch). Opportunistically convert an absurd number of instances of 'svm->vcpu' to direct uses of 'vcpu' to avoid pointless casting. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210205005750.3841462-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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