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KVM: VMX: Skip emulation required checks during pmode/rmode transitions

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Don't refresh "emulation required" when stuffing segments during
transitions to/from real mode when running without unrestricted guest.
The checks are unnecessary as vmx_set_cr0() unconditionally rechecks
"emulation required".  They also happen to be broken, as enter_pmode()
and enter_rmode() run with a stale vcpu->arch.cr0.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-29-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-07-13 09:33:06 -07:00 committed by Paolo Bonzini
parent 32437c2aea
commit 1dd7a4f18f
1 changed files with 12 additions and 6 deletions
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18
arch/x86/kvm/vmx/vmx.c
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@ -2719,6 +2719,8 @@ static __init int alloc_kvm_area(void)
return 0;
}
static void __vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);
static void fix_pmode_seg(struct kvm_vcpu *vcpu, int seg,
struct kvm_segment *save)
{
@ -2735,7 +2737,7 @@ static void fix_pmode_seg(struct kvm_vcpu *vcpu, int seg,
save->dpl = save->selector & SEGMENT_RPL_MASK;
save->s = 1;
}
vmx_set_segment(vcpu, save, seg);
__vmx_set_segment(vcpu, save, seg);
}
static void enter_pmode(struct kvm_vcpu *vcpu)
@ -2756,7 +2758,7 @@ static void enter_pmode(struct kvm_vcpu *vcpu)
vmx->rmode.vm86_active = 0;
vmx_set_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_TR], VCPU_SREG_TR);
__vmx_set_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_TR], VCPU_SREG_TR);
flags = vmcs_readl(GUEST_RFLAGS);
flags &= RMODE_GUEST_OWNED_EFLAGS_BITS;
@ -3291,7 +3293,7 @@ static u32 vmx_segment_access_rights(struct kvm_segment *var)
return ar;
}
void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
static void __vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
const struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
@ -3304,7 +3306,7 @@ void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
vmcs_write16(sf->selector, var->selector);
else if (var->s)
fix_rmode_seg(seg, &vmx->rmode.segs[seg]);
goto out;
return;
}
vmcs_writel(sf->base, var->base);
@ -3326,9 +3328,13 @@ void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
var->type |= 0x1; /* Accessed */
vmcs_write32(sf->ar_bytes, vmx_segment_access_rights(var));
}
out:
vmx->emulation_required = emulation_required(vcpu);
void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
{
__vmx_set_segment(vcpu, var, seg);
to_vmx(vcpu)->emulation_required = emulation_required(vcpu);
}
static void vmx_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)