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@xxxxxxxxxx>
---
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 */
