- 01 Aug, 2022 5 commits
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Oliver Upton authored
As it turns out, tests sometimes fail. When that is the case, packing the test assertion with as much relevant information helps track down the problem more quickly. Sharpen up the stat descriptor assertions in kvm_binary_stats_test to more precisely describe the reason for the test assertion and which stat is to blame. Signed-off-by:
Oliver Upton <oupton@google.com> Reviewed-by:
Andrew Jones <andrew.jones@linux.dev> Message-Id: <20220719143134.3246798-3-oliver.upton@linux.dev> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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Oliver Upton authored
In order to provide more useful test assertions that describe the broken stats descriptor, perform sanity check on the stat name before any other descriptor field. While at it, avoid dereferencing the name field if the sanity check fails as it is more likely to contain garbage. Signed-off-by:
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Paolo Bonzini authored
The last use of 'pfn' went away with the same-named argument to host_pfn_mapping_level; now that the hugepage level is obtained exclusively from the host page tables, kvm_mmu_zap_collapsible_spte does not need to know host pfns at all. Fixes: a8ac499b ("KVM: x86/mmu: Don't require refcounted "struct page" to create huge SPTEs") Signed-off-by:
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarmPaolo Bonzini authored
KVM/arm64 updates for 5.20: - Unwinder implementations for both nVHE modes (classic and protected), complete with an overflow stack - Rework of the sysreg access from userspace, with a complete rewrite of the vgic-v3 view to allign with the rest of the infrastructure - Disagregation of the vcpu flags in separate sets to better track their use model. - A fix for the GICv2-on-v3 selftest - A small set of cosmetic fixes
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Paolo Bonzini authored
KVM/s390, KVM/x86 and common infrastructure changes for 5.20 x86: * Permit guests to ignore single-bit ECC errors * Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache * Intel IPI virtualization * Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS * PEBS virtualization * Simplify PMU emulation by just using PERF_TYPE_RAW events * More accurate event reinjection on SVM (avoid retrying instructions) * Allow getting/setting the state of the speaker port data bit * Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent * "Notify" VM exit (detect microarchitectural hangs) for Intel * Cleanups for MCE MSR emulation s390: * add an interface to provide a hypervisor dump for secure guests * improve selftests to use TAP interface * enable interpretive execution of zPCI instructions (for PCI passthrough) * First part of deferred teardown * CPU Topology * PV attestation * Minor fixes Generic: * new selftests API using struct kvm_vcpu instead of a (vm, id) tuple x86: * Use try_cmpxchg64 instead of cmpxchg64 * Bugfixes * Ignore benign host accesses to PMU MSRs when PMU is disabled * Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior * x86/MMU: Allow NX huge pages to be disabled on a per-vm basis * Port eager page splitting to shadow MMU as well * Enable CMCI capability by default and handle injected UCNA errors * Expose pid of vcpu threads in debugfs * x2AVIC support for AMD * cleanup PIO emulation * Fixes for LLDT/LTR emulation * Don't require refcounted "struct page" to create huge SPTEs x86 cleanups: * Use separate namespaces for guest PTEs and shadow PTEs bitmasks * PIO emulation * Reorganize rmap API, mostly around rmap destruction * Do not workaround very old KVM bugs for L0 that runs with nesting enabled * new selftests API for CPUID
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- 29 Jul, 2022 12 commits
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https://github.com/kvm-riscv/linuxPaolo Bonzini authored
KVM/riscv changes for 5.20 * Track ISA extensions used by Guest using bitmap * Added system instruction emulation framework * Added CSR emulation framework * Added gfp_custom flag in struct kvm_mmu_memory_cache * Added G-stage ioremap() and iounmap() functions * Added support for Svpbmt inside Guest
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Anup Patel authored
The Guest/VM can use Svpbmt in VS-stage page tables when allowed by the Hypervisor using the henvcfg.PBMTE bit. We add Svpbmt support for the KVM Guest/VM which can be enabled/disabled by the KVM user-space (QEMU/KVMTOOL) using the ISA extension ONE_REG interface. Signed-off-by:
Anup Patel <apatel@ventanamicro.com> Reviewed-by:
Atish Patra <atishp@rivosinc.com> Signed-off-by:
Anup Patel <anup@brainfault.org>
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Anup Patel authored
When the host has Svpbmt extension, we should use page based memory type 2 (i.e. IO) for IO mappings in the G-stage page table. To achieve this, we replace use of PAGE_KERNEL with PAGE_KERNEL_IO in the kvm_riscv_gstage_ioremap(). Signed-off-by:
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Anup Patel authored
The in-kernel AIA IMSIC support requires on-demand mapping / unmapping of Guest IMSIC address to Host IMSIC guest files. To help achieve this, we add kvm_riscv_stage2_ioremap() and kvm_riscv_stage2_iounmap() functions. These new functions for updating G-stage page table mappings will be called in atomic context so we have special "in_atomic" parameter for this purpose. Signed-off-by:
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Anup Patel authored
The kvm_mmu_topup_memory_cache() always uses GFP_KERNEL_ACCOUNT for memory allocation which prevents it's use in atomic context. To address this limitation of kvm_mmu_topup_memory_cache(), we add gfp_custom flag in struct kvm_mmu_memory_cache. When the gfp_custom flag is set to some GFP_xyz flags, the kvm_mmu_topup_memory_cache() will use that instead of GFP_KERNEL_ACCOUNT. Signed-off-by:
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Anup Patel authored
We add an extensible CSR emulation framework which is based upon the existing system instruction emulation. This will be useful to upcoming AIA, PMU, Nested and other virtualization features. The CSR emulation framework also has provision to emulate CSR in user space but this will be used only in very specific cases such as AIA IMSIC CSR emulation in user space or vendor specific CSR emulation in user space. By default, all CSRs not handled by KVM RISC-V will be redirected back to Guest VCPU as illegal instruction trap. Signed-off-by:
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Anup Patel authored
We will be emulating more system instructions in near future with upcoming AIA, PMU, Nested and other virtualization features. To accommodate above, we add an extensible system instruction emulation framework in vcpu_insn.c. Signed-off-by:
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Anup Patel authored
The instruction and CSR emulation for VCPU is going to grow over time due to upcoming AIA, PMU, Nested and other virtualization features. Let us factor-out VCPU instruction emulation from vcpu_exit.c to a separate source dedicated for this purpose. Signed-off-by:
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Nikolay Borisov authored
local_irq_disable provides stronger guarantees than preempt_disable so calling the latter is redundant when interrupts are disabled. Instead, explicitly disable preemption right before interrupts are enabled/disabled to ensure that the time accounted in guest_timing_exit_irqoff includes time taken by the guest or interrupts. Signed-off-by:
Nikolay Borisov <nborisov@suse.com> Signed-off-by:
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Nikolay Borisov authored
It can never fail so convey that fact explicitly by making the function void. Also in kvm_arch_init_vm it makes it clear that there no need to do any cleanup after kvm_riscv_gstage_vmid_init has been called. Signed-off-by:
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Zhang Jiaming authored
There is a spelling mistake in mmu.c and vcpu_exit.c. Fix it. Signed-off-by:
Zhang Jiaming <jiaming@nfschina.com> Signed-off-by:
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Atish Patra authored
Currently, the every vcpu only stores the ISA extensions in a unsigned long which is not scalable as number of extensions will continue to grow. Using a bitmap allows the ISA extension to support any number of extensions. The CONFIG one reg interface implementation is modified to support the bitmap as well. But it is meant only for base extensions. Thus, the first element of the bitmap array is sufficient for that interface. In the future, all the new multi-letter extensions must use the ISA_EXT one reg interface that allows enabling/disabling any extension now. Signed-off-by:
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- 28 Jul, 2022 23 commits
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Kai Huang authored
Now kvm_tdp_mmu_zap_leafs() only zaps leaf SPTEs but not any non-root pages within that GFN range anymore, so the comment around it isn't right. Fix it by shifting the comment from tdp_mmu_zap_leafs() instead of duplicating it, as tdp_mmu_zap_leafs() is static and is only called by kvm_tdp_mmu_zap_leafs(). Opportunistically tweak the blurb about SPTEs being cleared to (a) say "zapped" instead of "cleared" because "cleared" will be wrong if/when KVM allows a non-zero value for non-present SPTE (i.e. for Intel TDX), and (b) to clarify that a flush is needed if and only if a SPTE has been zapped since MMU lock was last acquired. Fixes: f47e5bbb ("KVM: x86/mmu: Zap only TDP MMU leafs in zap range and mmu_notifier unmap") Suggested-by:
Sean Christopherson <seanjc@google.com> Reviewed-by:
Kai Huang <kai.huang@intel.com> Message-Id: <20220728030452.484261-1-kai.huang@intel.com> Signed-off-by:
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Jarkko Sakkinen authored
As Virtual Machine Save Area (VMSA) is essential in troubleshooting attestation, dump it to the klog with the KERN_DEBUG level of priority. Cc: Jarkko Sakkinen <jarkko@kernel.org> Suggested-by:
Harald Hoyer <harald@profian.com> Signed-off-by:
Jarkko Sakkinen <jarkko@profian.com> Message-Id: <20220728050919.24113-1-jarkko@profian.com> Signed-off-by:
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Sean Christopherson authored
Treat the NX bit as valid when using NPT, as KVM will set the NX bit when the NX huge page mitigation is enabled (mindblowing) and trigger the WARN that fires on reserved SPTE bits being set. KVM has required NX support for SVM since commit b26a71a1 ("KVM: SVM: Refuse to load kvm_amd if NX support is not available") for exactly this reason, but apparently it never occurred to anyone to actually test NPT with the mitigation enabled. ------------[ cut here ]------------ spte = 0x800000018a600ee7, level = 2, rsvd bits = 0x800f0000001fe000 WARNING: CPU: 152 PID: 15966 at arch/x86/kvm/mmu/spte.c:215 make_spte+0x327/0x340 [kvm] Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 10.48.0 01/27/2022 RIP: 0010:make_spte+0x327/0x340 [kvm] Call Trace: <TASK> tdp_mmu_map_handle_target_level+0xc3/0x230 [kvm] kvm_tdp_mmu_map+0x343/0x3b0 [kvm] direct_page_fault+0x1ae/0x2a0 [kvm] kvm_tdp_page_fault+0x7d/0x90 [kvm] kvm_mmu_page_fault+0xfb/0x2e0 [kvm] npf_interception+0x55/0x90 [kvm_amd] svm_invoke_exit_handler+0x31/0xf0 [kvm_amd] svm_handle_exit+0xf6/0x1d0 [kvm_amd] vcpu_enter_guest+0xb6d/0xee0 [kvm] ? kvm_pmu_trigger_event+0x6d/0x230 [kvm] vcpu_run+0x65/0x2c0 [kvm] kvm_arch_vcpu_ioctl_run+0x355/0x610 [kvm] kvm_vcpu_ioctl+0x551/0x610 [kvm] __se_sys_ioctl+0x77/0xc0 __x64_sys_ioctl+0x1d/0x20 do_syscall_64+0x44/0xa0 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> ---[ end trace 0000000000000000 ]--- Cc: stable@vger.kernel.org Signed-off-by:
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Suravee Suthikulpanit authored
The commit 5413bcba ("KVM: x86: Add support for vICR APIC-write VM-Exits in x2APIC mode") introduces logic to prevent APIC write for offset other than ICR in kvm_apic_write_nodecode() function. This breaks x2AVIC support, which requires KVM to trap and emulate x2APIC MSR writes. Therefore, removes the warning and modify to logic to allow MSR write. Fixes: 5413bcba ("KVM: x86: Add support for vICR APIC-write VM-Exits in x2APIC mode") Cc: Zeng Guang <guang.zeng@intel.com> Suggested-by:
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Message-Id: <20220725053356.4275-1-suravee.suthikulpanit@amd.com> Signed-off-by:
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Suravee Suthikulpanit authored
AMD does not support APIC TSC-deadline timer mode. AVIC hardware will generate GP fault when guest kernel writes 1 to bits [18] of the APIC LVTT register (offset 0x32) to set the timer mode. (Note: bit 18 is reserved on AMD system). Therefore, always intercept and let KVM emulate the MSR accesses. Fixes: f3d7c8aa6882 ("KVM: SVM: Fix x2APIC MSRs interception") Signed-off-by: -
Sean Christopherson authored
Verify that KVM allows toggling VMX MSR bits to be "more" restrictive, and also allows restoring each MSR to KVM's original, less restrictive value. Signed-off-by:
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Sean Christopherson authored
Make UMIP an "allowed-1" bit CR4_FIXED1 MSR when KVM is emulating UMIP. KVM emulates UMIP for both L1 and L2, and so should enumerate that L2 is allowed to have CR4.UMIP=1. Not setting the bit doesn't immediately break nVMX, as KVM does set/clear the bit in CR4_FIXED1 in response to a guest CPUID update, i.e. KVM will correctly (dis)allow nested VM-Entry based on whether or not UMIP is exposed to L1. That said, KVM should enumerate the bit as being allowed from time zero, e.g. userspace will see the wrong value if the MSR is read before CPUID is written. Fixes: 0367f205 ("KVM: vmx: add support for emulating UMIP") Signed-off-by:
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Paolo Bonzini authored
This reverts commit 03a8871a. Since commit 03a8871a ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL VM-{Entry,Exit} control"), KVM has taken ownership of the "load IA32_PERF_GLOBAL_CTRL" VMX entry/exit control bits, trying to set these bits in the IA32_VMX_TRUE_{ENTRY,EXIT}_CTLS MSRs if the guest's CPUID supports the architectural PMU (CPUID[EAX=0Ah].EAX[7:0]=1), and clear otherwise. This was a misguided attempt at mimicking what commit 5f76f6f5 ("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled", 2018-10-01) did for MPX. However, that commit was a workaround for another KVM bug and not something that should be imitated. Mucking with the VMX MSRs creates a subtle, difficult to maintain ABI as KVM must ensure that any internal changes, e.g. to how KVM handles _any_ guest CPUID changes, yield the same functional result. Therefore, KVM's policy is to let userspace have full control of the guest vCPU model so long as the host kernel is not at risk. Now that KVM really truly ensures kvm_set_msr() will succeed by loading PERF_GLOBAL_CTRL if and only if it exists, revert KVM's misguided and roundabout behavior. Signed-off-by:
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Sean Christopherson authored
Attempt to load PERF_GLOBAL_CTRL during nested VM-Enter/VM-Exit if and only if the MSR exists (according to the guest vCPU model). KVM has very misguided handling of VM_{ENTRY,EXIT}_LOAD_IA32_PERF_GLOBAL_CTRL and attempts to force the nVMX MSR settings to match the vPMU model, i.e. to hide/expose the control based on whether or not the MSR exists from the guest's perspective. KVM's modifications fail to handle the scenario where the vPMU is hidden from the guest _after_ being exposed to the guest, e.g. by userspace doing multiple KVM_SET_CPUID2 calls, which is allowed if done before any KVM_RUN. nested_vmx_pmu_refresh() is called if and only if there's a recognized vPMU, i.e. KVM will leave the bits in the allow state and then ultimately reject the MSR load and WARN. KVM should not force the VMX MSRs in the first place. KVM taking control of the MSRs was a misguided attempt at mimicking what commit 5f76f6f5 ("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled", 2018-10-01) did for MPX. However, the MPX commit was a workaround for another KVM bug and not something that should be imitated (and it should never been done in the first place). In other words, KVM's ABI _should_ be that userspace has full control over the MSRs, at which point triggering the WARN that loading the MSR must not fail is trivial. The intent of the WARN is still valid; KVM has consistency checks to ensure that vmcs12->{guest,host}_ia32_perf_global_ctrl is valid. The problem is that '0' must be considered a valid value at all times, and so the simple/obvious solution is to just not actually load the MSR when it does not exist. It is userspace's responsibility to provide a sane vCPU model, i.e. KVM is well within its ABI and Intel's VMX architecture to skip the loads if the MSR does not exist. Fixes: 03a8871a ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL VM-{Entry,Exit} control") Cc: stable@vger.kernel.org Signed-off-by: -
Sean Christopherson authored
Add a helper to check of the guest PMU has PERF_GLOBAL_CTRL, which is unintuitive _and_ diverges from Intel's architecturally defined behavior. Even worse, KVM currently implements the check using two different (but equivalent) checks, _and_ there has been at least one attempt to add a _third_ flavor. Cc: stable@vger.kernel.org Signed-off-by:
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Sean Christopherson authored
Mark all MSR_CORE_PERF_GLOBAL_CTRL and MSR_CORE_PERF_GLOBAL_OVF_CTRL bits as reserved if there is no guest vPMU. The nVMX VM-Entry consistency checks do not check for a valid vPMU prior to consuming the masks via kvm_valid_perf_global_ctrl(), i.e. may incorrectly allow a non-zero mask to be loaded via VM-Enter or VM-Exit (well, attempted to be loaded, the actual MSR load will be rejected by intel_is_valid_msr()). Fixes: f5132b01 ("KVM: Expose a version 2 architectural PMU to a guests") Cc: stable@vger.kernel.org Signed-off-by:
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Paolo Bonzini authored
Since commit 5f76f6f5 ("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled"), KVM has taken ownership of the "load IA32_BNDCFGS" and "clear IA32_BNDCFGS" VMX entry/exit controls, trying to set these bits in the IA32_VMX_TRUE_{ENTRY,EXIT}_CTLS MSRs if the guest's CPUID supports MPX, and clear otherwise. The intent of the patch was to apply it to L0 in order to work around L1 kernels that lack the fix in commit 691bd434 ("kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS", 2017-07-04): by hiding the control bits from L0, L1 hides BNDCFGS from KVM_GET_MSR_INDEX_LIST, and the L1 bug is neutralized even in the lack of commit 691bd434. This was perhaps a sensible kludge at the time, but a horrible idea in the long term and in fact it has not been extended to other CPUID bits like these: X86_FEATURE_LM => VM_EXIT_HOST_ADDR_SPACE_SIZE, VM_ENTRY_IA32E_MODE, VMX_MISC_SAVE_EFER_LMA X86_FEATURE_TSC => CPU_BASED_RDTSC_EXITING, CPU_BASED_USE_TSC_OFFSETTING, SECONDARY_EXEC_TSC_SCALING X86_FEATURE_INVPCID_SINGLE => SECONDARY_EXEC_ENABLE_INVPCID X86_FEATURE_MWAIT => CPU_BASED_MONITOR_EXITING, CPU_BASED_MWAIT_EXITING X86_FEATURE_INTEL_PT => SECONDARY_EXEC_PT_CONCEAL_VMX, SECONDARY_EXEC_PT_USE_GPA, VM_EXIT_CLEAR_IA32_RTIT_CTL, VM_ENTRY_LOAD_IA32_RTIT_CTL X86_FEATURE_XSAVES => SECONDARY_EXEC_XSAVES These days it's sort of common knowledge that any MSR in KVM_GET_MSR_INDEX_LIST must allow *at least* setting it with KVM_SET_MSR to a default value, so it is unlikely that something like commit 5f76f6f5 will be needed again. So revert it, at the potential cost of breaking L1s with a 6 year old kernel. While in principle the L0 owner doesn't control what runs on L1, such an old hypervisor would probably have many other bugs. Signed-off-by:
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Sean Christopherson authored
Restrict the nVMX MSRs based on KVM's config, not based on the guest's current config. Using the guest's config to audit the new config prevents userspace from restoring the original config (KVM's config) if at any point in the past the guest's config was restricted in any way. Fixes: 62cc6b9d ("KVM: nVMX: support restore of VMX capability MSRs") Cc: stable@vger.kernel.org Cc: David Matlack <dmatlack@google.com> Signed-off-by:
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Sean Christopherson authored
Rename the exit handlers for VMXON and VMXOFF to match the instruction names, the terms "vmon" and "vmoff" are not used anywhere in Intel's documentation, nor are they used elsehwere in KVM. Sadly, the exit reasons are exposed to userspace and so cannot be renamed without breaking userspace. :-( Fixes: ec378aee ("KVM: nVMX: Implement VMXON and VMXOFF") Signed-off-by:
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Sean Christopherson authored
Inject a #UD if L1 attempts VMXON with a CR0 or CR4 that is disallowed per the associated nested VMX MSRs' fixed0/1 settings. KVM cannot rely on hardware to perform the checks, even for the few checks that have higher priority than VM-Exit, as (a) KVM may have forced CR0/CR4 bits in hardware while running the guest, (b) there may incompatible CR0/CR4 bits that have lower priority than VM-Exit, e.g. CR0.NE, and (c) userspace may have further restricted the allowed CR0/CR4 values by manipulating the guest's nested VMX MSRs. Note, despite a very strong desire to throw shade at Jim, commit 70f3aac9 ("kvm: nVMX: Remove superfluous VMX instruction fault checks") is not to blame for the buggy behavior (though the comment...). That commit only removed the CR0.PE, EFLAGS.VM, and COMPATIBILITY mode checks (though it did erroneously drop the CPL check, but that has already been remedied). KVM may force CR0.PE=1, but will do so only when also forcing EFLAGS.VM=1 to emulate Real Mode, i.e. hardware will still #UD. Link: https://bugzilla.kernel.org/show_bug.cgi?id=216033 Fixes: ec378aee ("KVM: nVMX: Implement VMXON and VMXOFF") Reported-by:
Eric Li <ercli@ucdavis.edu> Cc: stable@vger.kernel.org Signed-off-by:
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Sean Christopherson authored
Check that the guest (L2) and host (L1) CR4 values that would be loaded by nested VM-Enter and VM-Exit respectively are valid with respect to KVM's (L0 host) allowed CR4 bits. Failure to check KVM reserved bits would allow L1 to load an illegal CR4 (or trigger hardware VM-Fail or failed VM-Entry) by massaging guest CPUID to allow features that are not supported by KVM. Amusingly, KVM itself is an accomplice in its doom, as KVM adjusts L1's MSR_IA32_VMX_CR4_FIXED1 to allow L1 to enable bits for L2 based on L1's CPUID model. Note, although nested_{guest,host}_cr4_valid() are _currently_ used if and only if the vCPU is post-VMXON (nested.vmxon == true), that may not be true in the future, e.g. emulating VMXON has a bug where it doesn't check the allowed/required CR0/CR4 bits. Cc: stable@vger.kernel.org Fixes: 3899152c ("KVM: nVMX: fix checks on CR{0,4} during virtual VMX operation") Signed-off-by: -
Sean Christopherson authored
Split the common x86 parts of kvm_is_valid_cr4(), i.e. the reserved bits checks, into a separate helper, __kvm_is_valid_cr4(), and export only the inner helper to vendor code in order to prevent nested VMX from calling back into vmx_is_valid_cr4() via kvm_is_valid_cr4(). On SVM, this is a nop as SVM doesn't place any additional restrictions on CR4. On VMX, this is also currently a nop, but only because nested VMX is missing checks on reserved CR4 bits for nested VM-Enter. That bug will be fixed in a future patch, and could simply use kvm_is_valid_cr4() as-is, but nVMX has _another_ bug where VMXON emulation doesn't enforce VMX's restrictions on CR0/CR4. The cleanest and most intuitive way to fix the VMXON bug is to use nested_host_cr{0,4}_valid(). If the CR4 variant routes through kvm_is_valid_cr4(), using nested_host_cr4_valid() won't do the right thing for the VMXON case as vmx_is_valid_cr4() enforces VMX's restrictions if and only if the vCPU is post-VMXON. Cc: stable@vger.kernel.org Signed-off-by: -
Sean Christopherson authored
Add a command line option to dirty_log_perf_test to run vCPUs for the entire duration of disabling dirty logging. By default, the test stops running runs vCPUs before disabling dirty logging, which is faster but less interesting as it doesn't stress KVM's handling of contention between page faults and the zapping of collapsible SPTEs. Enabling the flag also lets the user verify that KVM is indeed rebuilding zapped SPTEs as huge pages by checking KVM's pages_{1g,2m,4k} stats. Without vCPUs to fault in the zapped SPTEs, the stats will show that KVM is zapping pages, but they never show whether or not KVM actually allows huge pages to be recreated. Note! Enabling the flag can _significantly_ increase runtime, especially if the thread that's disabling dirty logging doesn't have a dedicated pCPU, e.g. if all pCPUs are used to run vCPUs. Signed-off-by: -
Sean Christopherson authored
When zapping collapsible SPTEs in the TDP MMU, don't bottom out on a leaf SPTE now that KVM doesn't require a PFN to compute the host mapping level, i.e. now that there's no need to first find a leaf SPTE and then step back up. Drop the now unused tdp_iter_step_up(), as it is not the safest of helpers (using any of the low level iterators requires some understanding of the various side effects). Signed-off-by:
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Sean Christopherson authored
Add a comment to document how host_pfn_mapping_level() can be used safely, as the line between safe and dangerous is quite thin. E.g. if KVM were to ever support in-place promotion to create huge pages, consuming the level is safe if the caller holds mmu_lock and checks that there's an existing _leaf_ SPTE, but unsafe if the caller only checks that there's a non-leaf SPTE. Opportunistically tweak the existing comments to explicitly document why KVM needs to use READ_ONCE(). No functional change intended. Signed-off-by:
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Sean Christopherson authored
Drop the requirement that a pfn be backed by a refcounted, compound or or ZONE_DEVICE, struct page, and instead rely solely on the host page tables to identify huge pages. The PageCompound() check is a remnant of an old implementation that identified (well, attempt to identify) huge pages without walking the host page tables. The ZONE_DEVICE check was added as an exception to the PageCompound() requirement. In other words, neither check is actually a hard requirement, if the primary has a pfn backed with a huge page, then KVM can back the pfn with a huge page regardless of the backing store. Dropping the @pfn parameter will also allow KVM to query the max host mapping level without having to first get the pfn, which is advantageous for use outside of the page fault path where KVM wants to take action if and only if a page can be mapped huge, i.e. avoids the pfn lookup for gfns that can't be backed with a huge page. Cc: Mingwei Zhang <mizhang@google.com> Signed-off-by:
Mingwei Zhang <mizhang@google.com> Message-Id: <20220715232107.3775620-2-seanjc@google.com> Signed-off-by:
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Sean Christopherson authored
Restrict the mapping level for SPTEs based on the guest MTRRs if and only if KVM may actually use the guest MTRRs to compute the "real" memtype. For all forms of paging, guest MTRRs are purely virtual in the sense that they are completely ignored by hardware, i.e. they affect the memtype only if software manually consumes them. The only scenario where KVM consumes the guest MTRRs is when shadow_memtype_mask is non-zero and the guest has non-coherent DMA, in all other cases KVM simply leaves the PAT field in SPTEs as '0' to encode WB memtype. Note, KVM may still ultimately ignore guest MTRRs, e.g. if the backing pfn is host MMIO, but false positives are ok as they only cause a slight performance blip (unless the guest is doing weird things with its MTRRs, which is extremely unlikely). Signed-off-by:
Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20220715230016.3762909-5-seanjc@google.com> Signed-off-by:
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Sean Christopherson authored
Add shadow_memtype_mask to capture that EPT needs a non-zero memtype mask instead of relying on TDP being enabled, as NPT doesn't need a non-zero mask. This is a glorified nop as kvm_x86_ops.get_mt_mask() returns zero for NPT anyways. No functional change intended. Signed-off-by:
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