Messages in this thread | | | From | Wei Huang <> | Subject | Re: [PATCH v3 0/4] Handle #GP for SVM execution instructions | Date | Tue, 26 Jan 2021 09:05:22 -0600 |
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On 1/26/21 5:39 AM, Paolo Bonzini wrote: > On 26/01/21 09:18, Wei Huang wrote: >> While running SVM related instructions (VMRUN/VMSAVE/VMLOAD), some AMD >> CPUs check EAX against reserved memory regions (e.g. SMM memory on host) >> before checking VMCB's instruction intercept. If EAX falls into such >> memory areas, #GP is triggered before #VMEXIT. This causes unexpected #GP >> under nested virtualization. To solve this problem, this patchset makes >> KVM trap #GP and emulate these SVM instuctions accordingly. >> >> Also newer AMD CPUs will change this behavior by triggering #VMEXIT >> before #GP. This change is indicated by CPUID_0x8000000A_EDX[28]. Under >> this circumstance, #GP interception is not required. This patchset >> supports >> the new feature. >> >> This patchset has been verified with vmrun_errata_test and >> vmware_backdoor >> tests of kvm_unit_test on the following configs. Also it was verified >> that >> vmware_backdoor can be turned on under nested on nested. >> * Current CPU: nested, nested on nested >> * New CPU with X86_FEATURE_SVME_ADDR_CHK: nested, nested on nested >> >> v2->v3: >> * Change the decode function name to x86_decode_emulated_instruction() >> * Add a new variable, svm_gp_erratum_intercept, to control >> interception >> * Turn on VM's X86_FEATURE_SVME_ADDR_CHK feature in svm_set_cpu_caps() >> * Fix instruction emulation for vmware_backdoor under nested-on-nested >> * Minor comment fixes >> >> v1->v2: >> * Factor out instruction decode for sharing >> * Re-org gp_interception() handling for both #GP and vmware_backdoor >> * Use kvm_cpu_cap for X86_FEATURE_SVME_ADDR_CHK feature support >> * Add nested on nested support >> >> Thanks, >> -Wei >> >> Wei Huang (4): >> KVM: x86: Factor out x86 instruction emulation with decoding >> KVM: SVM: Add emulation support for #GP triggered by SVM instructions >> KVM: SVM: Add support for SVM instruction address check change >> KVM: SVM: Support #GP handling for the case of nested on nested >> >> arch/x86/include/asm/cpufeatures.h | 1 + >> arch/x86/kvm/svm/svm.c | 128 +++++++++++++++++++++++++---- >> arch/x86/kvm/x86.c | 62 ++++++++------ >> arch/x86/kvm/x86.h | 2 + >> 4 files changed, 152 insertions(+), 41 deletions(-) >> > > Queued, thanks.
Thanks. BTW because we use kvm_cpu_cap_set() in svm_set_cpu_caps(). This will be reflected into the CPUID received by QEMU. QEMU needs a one-line patch to declare the new feature. I will send it out this morning.
-Wei
> > Paolo >
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