Initialize constant VMCS state in vcpu_vcpu_reset() instead of in
vmx_vcpu_create(), which allows for the removal of the open coded "vCPU
load" sequence since ->vcpu_reset() is invoked while the vCPU is properly
loaded (which is the entire point of vCPU reset...).
Deferring initialization is effectively a nop as it's impossible to
safely access the VMCS between the current call site and its new home, as
both the vCPU and the pCPU are put immediately after init_vmcs(), i.e.
the VMCS isn't guaranteed to be loaded.
Note, task preemption is not a problem as vmx_sched_in() _can't_ touch
the VMCS as ->sched_in() is invoked before the vCPU, and thus VMCS, is
reloaded. I.e. the preemption path also can't consume VMCS state.
Reviewed-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 0f5e97a904e5..26c0e776827c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4293,10 +4293,6 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
#define VMX_XSS_EXIT_BITMAP 0
-/*
- * Noting that the initialization of Guest-state Area of VMCS is in
- * vmx_vcpu_reset().
- */
static void init_vmcs(struct vcpu_vmx *vmx)
{
if (nested)
@@ -4395,6 +4391,9 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
u32 eax, dummy;
u64 cr0;
+ if (!init_event)
+ init_vmcs(vmx);
+
vmx->rmode.vm86_active = 0;
vmx->spec_ctrl = 0;
@@ -6782,7 +6781,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
{
struct vmx_uret_msr *tsx_ctrl;
struct vcpu_vmx *vmx;
- int i, cpu, err;
+ int i, err;
BUILD_BUG_ON(offsetof(struct vcpu_vmx, vcpu) != 0);
vmx = to_vmx(vcpu);
@@ -6844,12 +6843,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
vmx->msr_bitmap_mode = 0;
vmx->loaded_vmcs = &vmx->vmcs01;
- cpu = get_cpu();
- vmx_vcpu_load(vcpu, cpu);
- vcpu->cpu = cpu;
- init_vmcs(vmx);
- vmx_vcpu_put(vcpu);
- put_cpu();
+
if (cpu_need_virtualize_apic_accesses(vcpu)) {
err = alloc_apic_access_page(vcpu->kvm);
if (err)
--
2.32.0.93.g670b81a890-goog
