github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-31 10:33:41 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

KVM: nVMX: Switch to vmcs01 to update TPR threshold on-demand if L2 is active

Browse Source 
If KVM updates L1's TPR Threshold while L2 is active, temporarily load
vmcs01 and immediately update TPR_THRESHOLD instead of deferring the
update until the next nested VM-Exit.  Deferring the TPR Threshold update
is relatively straightforward, but for several APICv related updates,
deferring updates creates ordering and state consistency problems, e.g.
KVM at-large thinks APICv is enabled, but vmcs01 is still running with
stale (and effectively unknown) state.

Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://patch.msgid.link/20260109034532.1012993-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2026-01-08 19:45:27 -08:00
parent 3e013d0a70
commit 51ca274607
3 changed files with 3 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/kvm/vmx/nested.c
View File

@ -2402,7 +2402,6 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
exec_control &= ~CPU_BASED_TPR_SHADOW;
exec_control |= vmcs12->cpu_based_vm_exec_control;
vmx->nested.l1_tpr_threshold = -1;
if (exec_control & CPU_BASED_TPR_SHADOW)
vmcs_write32(TPR_THRESHOLD, vmcs12->tpr_threshold);
#ifdef CONFIG_X86_64
@ -5123,9 +5122,6 @@ void __nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
if (kvm_caps.has_tsc_control)
vmcs_write64(TSC_MULTIPLIER, vcpu->arch.tsc_scaling_ratio);
if (vmx->nested.l1_tpr_threshold != -1)
vmcs_write32(TPR_THRESHOLD, vmx->nested.l1_tpr_threshold);
if (vmx->nested.change_vmcs01_virtual_apic_mode) {
vmx->nested.change_vmcs01_virtual_apic_mode = false;
vmx_set_virtual_apic_mode(vcpu);

7
arch/x86/kvm/vmx/vmx.c
View File

@ -6836,11 +6836,10 @@ void vmx_update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr)
nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW))
return;
guard(vmx_vmcs01)(vcpu);
tpr_threshold = (irr == -1 || tpr < irr) ? 0 : irr;
if (is_guest_mode(vcpu))
to_vmx(vcpu)->nested.l1_tpr_threshold = tpr_threshold;
else
vmcs_write32(TPR_THRESHOLD, tpr_threshold);
vmcs_write32(TPR_THRESHOLD, tpr_threshold);
}
void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu)

3
arch/x86/kvm/vmx/vmx.h
View File

@ -184,9 +184,6 @@ struct nested_vmx {
u64 pre_vmenter_ssp;
u64 pre_vmenter_ssp_tbl;
/* to migrate it to L1 if L2 writes to L1's CR8 directly */
int l1_tpr_threshold;
u16 vpid02;
u16 last_vpid;