| Message ID | 20210920235134.101970-2-krish.sadhukhan@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | nSVM: Check for optional commands and reserved encodins of TLB_CONTROL in nested guests | expand |
On 21/09/21 01:51, Krish Sadhukhan wrote: > The FLUSHBYASID CPUID feature controls the availability of commands > 0x3 and 0x7 of TLB_CONTROL. If FLUSHBYASID is supported by the VCPU, > those TLB_CONTROL commands will be available to nested guests. The hypervisor would have to implement them. Right now the VMCB12 tlb_ctl is not used. /* Also overwritten later if necessary. */ svm->vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING; So this won't work. Paolo > Therefore, > expose FLUSHBYASID CPUID feature to nested guests. > > Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> > --- > arch/x86/kvm/svm/svm.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 1a70e11f0487..0f8748af8569 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -931,6 +931,9 @@ static __init void svm_set_cpu_caps(void) > > /* Nested VM can receive #VMEXIT instead of triggering #GP */ > kvm_cpu_cap_set(X86_FEATURE_SVME_ADDR_CHK); > + > + if (boot_cpu_has(X86_FEATURE_FLUSHBYASID)) > + kvm_cpu_cap_set(X86_FEATURE_FLUSHBYASID); > } > > /* CPUID 0x80000008 */ >
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 1a70e11f0487..0f8748af8569 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -931,6 +931,9 @@ static __init void svm_set_cpu_caps(void) /* Nested VM can receive #VMEXIT instead of triggering #GP */ kvm_cpu_cap_set(X86_FEATURE_SVME_ADDR_CHK); + + if (boot_cpu_has(X86_FEATURE_FLUSHBYASID)) + kvm_cpu_cap_set(X86_FEATURE_FLUSHBYASID); } /* CPUID 0x80000008 */
The FLUSHBYASID CPUID feature controls the availability of commands 0x3 and 0x7 of TLB_CONTROL. If FLUSHBYASID is supported by the VCPU, those TLB_CONTROL commands will be available to nested guests. Therefore, expose FLUSHBYASID CPUID feature to nested guests. Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> --- arch/x86/kvm/svm/svm.c | 3 +++ 1 file changed, 3 insertions(+)