Messages in this thread | | | Subject | Re: [PATCH 3/9] KVM: x86: add pcommit support | From | Xiao Guangrong <> | Date | Tue, 8 Sep 2015 22:17:19 +0800 |
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On 09/07/2015 07:18 PM, Paolo Bonzini wrote:
>> >> +static int handle_pcommit(struct kvm_vcpu *vcpu) >> +{ >> + /* we never catch pcommit instruct for L1 guest. */ >> + BUG(); > > Please WARN instead. >
Okay.
>> + return 1; >> +} >> + >> /* >> * The exit handlers return 1 if the exit was handled fully and guest execution >> * may resume. Otherwise they set the kvm_run parameter to indicate what needs >> @@ -7258,6 +7269,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = { >> [EXIT_REASON_XSAVES] = handle_xsaves, >> [EXIT_REASON_XRSTORS] = handle_xrstors, >> [EXIT_REASON_PML_FULL] = handle_pml_full, >> + [EXIT_REASON_PCOMMIT] = handle_pcommit, >> }; >> >> static const int kvm_vmx_max_exit_handlers = >> @@ -7559,6 +7571,8 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu) >> * the XSS exit bitmap in vmcs12. >> */ >> return nested_cpu_has2(vmcs12, SECONDARY_EXEC_XSAVES); >> + case EXIT_REASON_PCOMMIT: >> + return nested_cpu_has2(vmcs12, SECONDARY_EXEC_PCOMMIT); >> default: >> return true; >> } >> @@ -8688,6 +8702,10 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu) >> if (best) >> best->ebx &= ~bit(X86_FEATURE_INVPCID); >> } >> + >> + if (!guest_cpuid_has_pcommit(vcpu) && nested) >> + vmx->nested.nested_vmx_secondary_ctls_high &= >> + ~SECONDARY_EXEC_PCOMMIT; > > Why is this needed? >
If pcommit is not allowed in L1 guest, L1 is not allowed to intercept pcommit for L2.
BTW, the spec saied:
| IA32_VMX_PROCBASED_CTLS2[53] (which enumerates support for the 1-setting of “PCOMMIT exiting”) is | always the same as CPUID.07H:EBX.PCOMMIT[bit 22]. Thus, software can set “PCOMMIT exiting” to 1 | if and only if the PCOMMIT instruction is enumerated via CPUID
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