- 30 Sep, 2021 22 commits
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Sean Christopherson authored
Move vCPU RESET emulation, including initializating of select VMCS state, to vmx_vcpu_reset(). Drop the open coded "vCPU load" sequence, as ->vcpu_reset() is invoked while the vCPU is properly loaded (which is kind of the point of ->vcpu_reset()...). Hopefully KVM will someday expose a dedicated RESET ioctl(), and in the meantime separating "create" from "RESET" is a nice cleanup. Deferring VMCS initialization is effectively a nop as it's impossible to safely access the VMCS between the current call site and its new home, as both the vCPU and the pCPU are put immediately after init_vmcs(), i.e. the VMCS isn't guaranteed to be loaded. Note, task preemption is not a problem as vmx_sched_in() _can't_ touch the VMCS as ->sched_in() is invoked before the vCPU, and thus VMCS, is reloaded. I.e. the preemption path also can't consume VMCS state. Cc: Reiji Watanabe <reijiw@google.com> Signed-off-by:
Sean Christopherson <seanjc@google.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20210921000303.400537-9-seanjc@google.com> Signed-off-by:
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Sean Christopherson authored
Don't zero out user return and nested MSRs during vCPU creation, and instead rely on vcpu_vmx being zero-allocated. Explicitly zeroing MSRs is not wrong, and is in fact necessary if KVM ever emulates vCPU RESET outside of vCPU creation, but zeroing only a subset of MSRs is confusing. Poking directly into KVM's backing is also undesirable in that it doesn't scale and is error prone. Ideally KVM would have a common RESET path for all MSRs, e.g. by expanding kvm_set_msr(), which would obviate the need for this out-of-bad code (to support standalone RESET). No functional change intended. Signed-off-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:
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Sean Christopherson authored
Move the few bits of relevant fx_init() code into kvm_arch_vcpu_create(), dropping the superfluous check on vcpu->arch.guest_fpu that was blindly and wrongly added by commit ed02b213 ("KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest"). Note, KVM currently allocates and then frees FPU state for SEV-ES guests, rather than avoid the allocation in the first place. While that approach is inarguably inefficient and unnecessary, it's a cleanup for the future. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Drop code to initialize XCR0 during fx_init(), a.k.a. vCPU creation, as XCR0 has been initialized during kvm_vcpu_reset() (for RESET) since commit a554d207 ("KVM: X86: Processor States following Reset or INIT"). Back when XCR0 support was added by commit 2acf923e ("KVM: VMX: Enable XSAVE/XRSTOR for guest"), KVM didn't differentiate between RESET and INIT. Ignoring the fact that calling fx_init() for INIT is obviously wrong, e.g. FPU state after INIT is not the same as after RESET, setting XCR0 in fx_init() was correct. Eventually fx_init() got moved to kvm_arch_vcpu_init(), a.k.a. vCPU creation (ignore the terrible name) by commit 0ee6a517 ("x86/fpu, kvm: Simplify fx_init()"). Finally, commit 95a0d01e ("KVM: x86: Move all vcpu init code into kvm_arch_vcpu_create()") killed off kvm_arch_vcpu_init(), leaving behind the oddity of redundant setting of guest state during vCPU creation. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Drop code to set CR0.ET for the guest during initialization of the guest FPU. The code was added as a misguided bug fix by commit 380102c8 ("KVM Set the ET flag in CR0 after initializing FX") to resolve an issue where vcpu->cr0 (now vcpu->arch.cr0) was not correctly initialized on SVM systems. While init_vmcb() did set CR0.ET, it only did so in the VMCB, and subtly did not update vcpu->cr0. Stuffing CR0.ET worked around the immediate problem, but did not fix the real bug of vcpu->cr0 and the VMCB being out of sync. That underlying bug was eventually remedied by commit 18fa000a ("KVM: SVM: Reset cr0 properly on vcpu reset"). No functional change intended. Signed-off-by:
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Sean Christopherson authored
Do not blindly mark all registers as available+dirty at RESET/INIT, and instead rely on writes to registers to go through the proper mutators or to explicitly mark registers as dirty. INIT in particular does not blindly overwrite all registers, e.g. select bits in CR0 are preserved across INIT, thus marking registers available+dirty without first reading the register from hardware is incorrect. In practice this is a benign bug as KVM doesn't let the guest control CR0 bits that are preserved across INIT, and all other true registers are explicitly written during the RESET/INIT flows. The PDPTRs and EX_INFO "registers" are not explicitly written, but accessing those values during RESET/INIT is nonsensical and would be a KVM bug regardless of register caching. Fixes: 66f7b72e ("KVM: x86: Make register state after reset conform to specification") [sean: !!! NOT FOR STABLE !!!] Signed-off-by:
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Sean Christopherson authored
Replace impressively complex "logic" for computing the page offset from CR3 when loading PDPTRs. Unlike other paging modes, the address held in CR3 for PAE paging is 32-byte aligned, i.e. occupies bits 31:5, thus bits 11:5 need to be used as the offset from the gfn when reading PDPTRs. The existing calculation originated in commit 1342d353 ("[PATCH] KVM: MMU: Load the pae pdptrs on cr3 change like the processor does"), which read the PDPTRs from guest memory as individual 8-byte loads. At the time, the so called "offset" was the base index of PDPTR0 as a _u64_, not a byte offset. Naming aside, the computation was useful and arguably simplified the overall flow. Unfortunately, when commit 195aefde ("KVM: Add general accessors to read and write guest memory") added accessors with offsets at byte granularity, the cleverness of the original code was lost and KVM was left with convoluted code for a simple operation. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Open code the call to mmu->translate_gpa() when loading nested PDPTRs and kill off the existing helper, kvm_read_guest_page_mmu(), to discourage incorrect use. Reading guest memory straight from an L2 GPA is extremely rare (as evidenced by the lack of users), as very few constructs in x86 specify physical addresses, even fewer are virtualized by KVM, and even fewer yet require emulation of L2 by L0 KVM. No functional change intended. Signed-off-by:
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Juergen Gross authored
KVM_MAX_VCPU_ID is not specifying the highest allowed vcpu-id, but the number of allowed vcpu-ids. This has already led to confusion, so rename KVM_MAX_VCPU_ID to KVM_MAX_VCPU_IDS to make its semantics more clear Suggested-by:
Eduardo Habkost <ehabkost@redhat.com> Signed-off-by:
Juergen Gross <jgross@suse.com> Signed-off-by:
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Juergen Gross authored
This reverts commit 76b4f357. The commit has the wrong reasoning, as KVM_MAX_VCPU_ID is not defining the maximum allowed vcpu-id as its name suggests, but the number of vcpu-ids. So revert this patch again. Suggested-by:
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Vitaly Kuznetsov authored
kvm_make_vcpus_request_mask() already disables preemption so just like kvm_make_all_cpus_request_except() it can be switched to using pre-allocated per-cpu cpumasks. This allows for improvements for both users of the function: in Hyper-V emulation code 'tlb_flush' can now be dropped from 'struct kvm_vcpu_hv' and kvm_make_scan_ioapic_request_mask() gets rid of dynamic allocation. cpumask_available() checks in kvm_make_vcpu_request() and kvm_kick_many_cpus() can now be dropped as they checks for an impossible condition: kvm_init() makes sure per-cpu masks are allocated. Signed-off-by:
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Vitaly Kuznetsov authored
Allocating cpumask dynamically in zalloc_cpumask_var() is not ideal. Allocation is somewhat slow and can (in theory and when CPUMASK_OFFSTACK) fail. kvm_make_all_cpus_request_except() already disables preemption so we can use pre-allocated per-cpu cpumasks instead. Signed-off-by:
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Vitaly Kuznetsov authored
Both remaining callers of kvm_make_vcpus_request_mask() pass 'NULL' for 'except' parameter so it can just be dropped. No functional change intended
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Vitaly Kuznetsov authored
Iterating over set bits in 'vcpu_bitmap' should be faster than going through all vCPUs, especially when just a few bits are set. Drop kvm_make_vcpus_request_mask() call from kvm_make_all_cpus_request_except() to avoid handling the special case when 'vcpu_bitmap' is NULL, move the code to kvm_make_all_cpus_request_except() itself. Signed-off-by:
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Vitaly Kuznetsov authored
In preparation to making kvm_make_vcpus_request_mask() use for_each_set_bit() switch kvm_hv_flush_tlb() to calling kvm_make_all_cpus_request() for 'all cpus' case. Note: kvm_make_all_cpus_request() (unlike kvm_make_vcpus_request_mask()) currently dynamically allocates cpumask on each call and this is suboptimal. Both kvm_make_all_cpus_request() and kvm_make_vcpus_request_mask() are going to be switched to using pre-allocated per-cpu masks. Reviewed-by:
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Yang Li authored
Use vma_pages function on vma object instead of explicit computation. Fix the following coccicheck warning: ./virt/kvm/kvm_main.c:3526:29-35: WARNING: Consider using vma_pages helper on vma Reported-by:
Abaci Robot <abaci@linux.alibaba.com> Signed-off-by:
Yang Li <yang.lee@linux.alibaba.com> Message-Id: <1632900526-119643-1-git-send-email-yang.lee@linux.alibaba.com> Signed-off-by:
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Vitaly Kuznetsov authored
Currently, 'vmx->nested.vmxon_ptr' is not reset upon VMXOFF emulation. This is not a problem per se as we never access it when !vmx->nested.vmxon. But this should be done to avoid any issue in the future. Also, initialize the vmxon_ptr when vcpu is created. Signed-off-by:
Yu Zhang <yu.c.zhang@linux.intel.com> Message-Id: <20210929175154.11396-3-yu.c.zhang@linux.intel.com> Signed-off-by:
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Yu Zhang authored
Clean up nested.c and vmx.c by using INVALID_GPA instead of "-1ull", to denote an invalid address in nested VMX. Affected addresses are the ones of VMXON region, current VMCS, VMCS link pointer, virtual- APIC page, ENCLS-exiting bitmap, and IO bitmap etc. Suggested-by:
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Sean Christopherson authored
Rework the CPU selection in the migration worker to ensure the specified number of migrations are performed when the test iteslf is affined to a subset of CPUs. The existing logic skips iterations if the target CPU is not in the original set of possible CPUs, which causes the test to fail if too many iterations are skipped. ==== Test Assertion Failure ==== rseq_test.c:228: i > (NR_TASK_MIGRATIONS / 2) pid=10127 tid=10127 errno=4 - Interrupted system call 1 0x00000000004018e5: main at rseq_test.c:227 2 0x00007fcc8fc66bf6: ?? ??:0 3 0x0000000000401959: _start at ??:? Only performed 4 KVM_RUNs, task stalled too much? Calculate the min/max possible CPUs as a cheap "best effort" to avoid high runtimes when the test is affined to a small percentage of CPUs. Alternatively, a list or xarray of the possible CPUs could be used, but even in a horrendously inefficient setup, such optimizations are not needed because the runtime is completely dominated by the cost of migrating the task, and the absolute runtime is well under a minute in even truly absurd setups, e.g. running on a subset of vCPUs in a VM that is heavily overcommited (16 vCPUs per pCPU). Fixes: 61e52f16 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs") Reported-by:Dongli Zhang <dongli.zhang@oracle.com> Signed-off-by:
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Sean Christopherson authored
Check whether a CPUID entry's index is significant before checking for a matching index to hack-a-fix an undefined behavior bug due to consuming uninitialized data. RESET/INIT emulation uses kvm_cpuid() to retrieve CPUID.0x1, which does _not_ have a significant index, and fails to initialize the dummy variable that doubles as EBX/ECX/EDX output _and_ ECX, a.k.a. index, input. Practically speaking, it's _extremely_ unlikely any compiler will yield code that causes problems, as the compiler would need to inline the kvm_cpuid() call to detect the uninitialized data, and intentionally hose the kernel, e.g. insert ud2, instead of simply ignoring the result of the index comparison. Although the sketchy "dummy" pattern was introduced in SVM by commit 66f7b72e ("KVM: x86: Make register state after reset conform to specification"), it wasn't actually broken until commit 7ff6c035 ("KVM: x86: Remove stateful CPUID handling") arbitrarily swapped the order of operations such that "index" was checked before the significant flag. Avoid consuming uninitialized data by reverting to checking the flag before the index purely so that the fix can be easily backported; the offending RESET/INIT code has been refactored, moved, and consolidated from vendor code to common x86 since the bug was introduced. A future patch will directly address the bad RESET/INIT behavior. The undefined behavior was detected by syzbot + KernelMemorySanitizer. BUG: KMSAN: uninit-value in cpuid_entry2_find arch/x86/kvm/cpuid.c:68 BUG: KMSAN: uninit-value in kvm_find_cpuid_entry arch/x86/kvm/cpuid.c:1103 BUG: KMSAN: uninit-value in kvm_cpuid+0x456/0x28f0 arch/x86/kvm/cpuid.c:1183 cpuid_entry2_find arch/x86/kvm/cpuid.c:68 [inline] kvm_find_cpuid_entry arch/x86/kvm/cpuid.c:1103 [inline] kvm_cpuid+0x456/0x28f0 arch/x86/kvm/cpuid.c:1183 kvm_vcpu_reset+0x13fb/0x1c20 arch/x86/kvm/x86.c:10885 kvm_apic_accept_events+0x58f/0x8c0 arch/x86/kvm/lapic.c:2923 vcpu_enter_guest+0xfd2/0x6d80 arch/x86/kvm/x86.c:9534 vcpu_run+0x7f5/0x18d0 arch/x86/kvm/x86.c:9788 kvm_arch_vcpu_ioctl_run+0x245b/0x2d10 arch/x86/kvm/x86.c:10020 Local variable ----dummy@kvm_vcpu_reset created at: kvm_vcpu_reset+0x1fb/0x1c20 arch/x86/kvm/x86.c:10812 kvm_apic_accept_events+0x58f/0x8c0 arch/x86/kvm/lapic.c:2923 Reported-by: syzbot+f3985126b746b3d59c9d@syzkaller.appspotmail.com Reported-by:
Alexander Potapenko <glider@google.com> Fixes: 2a24be79 ("KVM: VMX: Set EDX at INIT with CPUID.0x1, Family-Model-Stepping") Fixes: 7ff6c035 ("KVM: x86: Remove stateful CPUID handling") Cc: stable@vger.kernel.org Signed-off-by:
Jim Mattson <jmattson@google.com> Message-Id: <20210929222426.1855730-2-seanjc@google.com> Signed-off-by:
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Zelin Deng authored
hv_clock is preallocated to have only HVC_BOOT_ARRAY_SIZE (64) elements; if the PTP_SYS_OFFSET_PRECISE ioctl is executed on vCPUs whose index is 64 of higher, retrieving the struct pvclock_vcpu_time_info pointer with "src = &hv_clock[cpu].pvti" will result in an out-of-bounds access and a wild pointer. Change it to "this_cpu_pvti()" which is guaranteed to be valid. Fixes: 95a3d445 ("Switch kvmclock data to a PER_CPU variable") Signed-off-by:
Zelin Deng <zelin.deng@linux.alibaba.com> Cc: <stable@vger.kernel.org> Message-Id: <1632892429-101194-3-git-send-email-zelin.deng@linux.alibaba.com> Signed-off-by:
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Zelin Deng authored
There're other modules might use hv_clock_per_cpu variable like ptp_kvm, so move it into kvmclock.h and export the symbol to make it visiable to other modules. Signed-off-by:
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- 28 Sep, 2021 1 commit
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Oliver Upton authored
There is no need to clobber a register that is only being read from. Oops. Drop the XMM register from the clobbers list. Signed-off-by:
Oliver Upton <oupton@google.com> Message-Id: <20210927223621.50178-1-oupton@google.com> Signed-off-by:
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- 27 Sep, 2021 1 commit
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Zhenzhong Duan authored
When updating the host's mask for its MSR_IA32_TSX_CTRL user return entry, clear the mask in the found uret MSR instead of vmx->guest_uret_msrs[i]. Modifying guest_uret_msrs directly is completely broken as 'i' does not point at the MSR_IA32_TSX_CTRL entry. In fact, it's guaranteed to be an out-of-bounds accesses as is always set to kvm_nr_uret_msrs in a prior loop. By sheer dumb luck, the fallout is limited to "only" failing to preserve the host's TSX_CTRL_CPUID_CLEAR. The out-of-bounds access is benign as it's guaranteed to clear a bit in a guest MSR value, which are always zero at vCPU creation on both x86-64 and i386. Cc: stable@vger.kernel.org Fixes: 8ea8b8d6 ("KVM: VMX: Use common x86's uret MSR list as the one true list") Signed-off-by:
Zhenzhong Duan <zhenzhong.duan@intel.com> Reviewed-by:
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- 24 Sep, 2021 3 commits
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Paolo Bonzini authored
Merge tag 'kvmarm-fixes-5.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master KVM/arm64 fixes for 5.15, take #1 - Add missing FORCE target when building the EL2 object - Fix a PMU probe regression on some platforms
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Oliver Upton authored
Compiling the KVM selftests with clang emits the following warning: >> include/x86_64/processor.h:297:25: error: variable 'xmm0' is uninitialized when used here [-Werror,-Wuninitialized] >> return (unsigned long)xmm0; where xmm0 is accessed via an uninitialized register variable. Indeed, this is a misuse of register variables, which really should only be used for specifying register constraints on variables passed to inline assembly. Rather than attempting to read xmm registers via register variables, just explicitly perform the movq from the desired xmm register. Fixes: 783e9e51 ("kvm: selftests: add API testing infrastructure") Signed-off-by:
Ricardo Koller <ricarkol@google.com> Signed-off-by:
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Oliver Upton authored
While x86 does not require any additional setup to use the ucall infrastructure, arm64 needs to set up the MMIO address used to signal a ucall to userspace. rseq_test does not initialize the MMIO address, resulting in the test spinning indefinitely. Fix the issue by calling ucall_init() during setup. Fixes: 61e52f16 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs") Signed-off-by:
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- 23 Sep, 2021 7 commits
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Lai Jiangshan authored
There is no user of tlbs_dirty. Signed-off-by:
Lai Jiangshan <laijs@linux.alibaba.com> Signed-off-by:
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Lai Jiangshan authored
If gpte is changed from non-present to present, the guest doesn't need to flush tlb per SDM. So the host must synchronze sp before link it. Otherwise the guest might use a wrong mapping. For example: the guest first changes a level-1 pagetable, and then links its parent to a new place where the original gpte is non-present. Finally the guest can access the remapped area without flushing the tlb. The guest's behavior should be allowed per SDM, but the host kvm mmu makes it wrong. Fixes: 4731d4c7 ("KVM: MMU: out of sync shadow core") Signed-off-by:
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Lai Jiangshan authored
When kvm->tlbs_dirty > 0, some rmaps might have been deleted without flushing tlb remotely after kvm_sync_page(). If @gfn was writable before and it's rmaps was deleted in kvm_sync_page(), and if the tlb entry is still in a remote running VCPU, the @gfn is not safely protected. To fix the problem, kvm_sync_page() does the remote flush when needed to avoid the problem. Fixes: a4ee1ca4 ("KVM: MMU: delay flush all tlbs on sync_page path") Signed-off-by:
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Maxim Levitsky authored
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:
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Maxim Levitsky authored
GP SVM errata workaround made the #GP handler always emulate the SVM instructions. However these instructions #GP in case the operand is not 4K aligned, but the workaround code didn't check this and we ended up emulating these instructions anyway. This is only an emulation accuracy check bug as there is no harm for KVM to read/write unaligned vmcb images. Fixes: 82a11e9c ("KVM: SVM: Add emulation support for #GP triggered by SVM instructions") Signed-off-by:
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Maxim Levitsky authored
Test that if: * L1 disables virtual interrupt masking, and INTR intercept. * L1 setups a virtual interrupt to be injected to L2 and enters L2 with interrupts disabled, thus the virtual interrupt is pending. * Now an external interrupt arrives in L1 and since L1 doesn't intercept it, it should be delivered to L2 when it enables interrupts. to do this L0 (abuses) V_IRQ to setup an interrupt window, and returns to L2. * L2 enables interrupts. This should trigger the interrupt window, injection of the external interrupt and delivery of the virtual interrupt that can now be done. * Test that now L2 gets those interrupts. This is the test that demonstrates the issue that was fixed in the previous patch. Signed-off-by:
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Maxim Levitsky authored
In svm_clear_vintr we try to restore the virtual interrupt injection that might be pending, but we fail to restore the interrupt vector. Signed-off-by:
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- 22 Sep, 2021 6 commits
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Fares Mehanna authored
Intel PMU MSRs is in msrs_to_save_all[], so add AMD PMU MSRs to have a consistent behavior between Intel and AMD when using KVM_GET_MSRS, KVM_SET_MSRS or KVM_GET_MSR_INDEX_LIST. We have to add legacy and new MSRs to handle guests running without X86_FEATURE_PERFCTR_CORE. Signed-off-by:
Fares Mehanna <faresx@amazon.de> Message-Id: <20210915133951.22389-1-faresx@amazon.de> Signed-off-by:
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Maxim Levitsky authored
If L1 had invalid state on VM entry (can happen on SMM transactions when we enter from real mode, straight to nested guest), then after we load 'host' state from VMCS12, the state has to become valid again, but since we load the segment registers with __vmx_set_segment we weren't always updating emulation_required. Update emulation_required explicitly at end of load_vmcs12_host_state. Signed-off-by:
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Maxim Levitsky authored
It is possible that when non root mode is entered via special entry (!from_vmentry), that is from SMM or from loading the nested state, the L2 state could be invalid in regard to non unrestricted guest mode, but later it can become valid. (for example when RSM emulation restores segment registers from SMRAM) Thus delay the check to VM entry, where we will check this and fail. Signed-off-by:
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Maxim Levitsky authored
Since no actual VM entry happened, the VM exit information is stale. To avoid this, synthesize an invalid VM guest state VM exit. Suggested-by:
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Maxim Levitsky authored
Use return statements instead of nested if, and fix error path to free all the maps that were allocated. Suggested-by:
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Maxim Levitsky authored
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:
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