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KVM: x86: nSVM: correctly virtualize LBR msrs when L2 is running

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When L2 is running without LBR virtualization, we should ensure
that L1's LBR msrs continue to update as usual.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322174050.241850-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Maxim Levitsky
2022-03-22 19:40:45 +02:00
committed by Paolo Bonzini
parent ea91559b00
commit 1d5a1b5860
3 changed files with 93 additions and 19 deletions
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12
arch/x86/kvm/svm/nested.c
View File

@@ -536,6 +536,7 @@ void nested_vmcb02_compute_g_pat(struct vcpu_svm *svm)
static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12)
{
bool new_vmcb12 = false;
struct vmcb *vmcb01 = svm->vmcb01.ptr;
struct vmcb *vmcb02 = svm->nested.vmcb02.ptr;
nested_vmcb02_compute_g_pat(svm);
@@ -586,6 +587,9 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
svm->vcpu.arch.dr6 = svm->nested.save.dr6 | DR6_ACTIVE_LOW;
vmcb_mark_dirty(vmcb02, VMCB_DR);
}
if (unlikely(vmcb01->control.virt_ext & LBR_CTL_ENABLE_MASK))
svm_copy_lbrs(vmcb02, vmcb01);
}
static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
@@ -645,6 +649,9 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
vmcb02->control.event_inj = svm->nested.ctl.event_inj;
vmcb02->control.event_inj_err = svm->nested.ctl.event_inj_err;
vmcb02->control.virt_ext = vmcb01->control.virt_ext &
LBR_CTL_ENABLE_MASK;
if (!nested_vmcb_needs_vls_intercept(svm))
vmcb02->control.virt_ext |= VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK;
@@ -912,6 +919,11 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
svm_switch_vmcb(svm, &svm->vmcb01);
if (unlikely(vmcb01->control.virt_ext & LBR_CTL_ENABLE_MASK)) {
svm_copy_lbrs(vmcb01, vmcb02);
svm_update_lbrv(vcpu);
}
/*
* On vmexit the GIF is set to false and
* no event can be injected in L1.

96
arch/x86/kvm/svm/svm.c
View File

@@ -793,6 +793,17 @@ static void init_msrpm_offsets(void)
}
}
void svm_copy_lbrs(struct vmcb *to_vmcb, struct vmcb *from_vmcb)
{
to_vmcb->save.dbgctl = from_vmcb->save.dbgctl;
to_vmcb->save.br_from = from_vmcb->save.br_from;
to_vmcb->save.br_to = from_vmcb->save.br_to;
to_vmcb->save.last_excp_from = from_vmcb->save.last_excp_from;
to_vmcb->save.last_excp_to = from_vmcb->save.last_excp_to;
vmcb_mark_dirty(to_vmcb, VMCB_LBR);
}
static void svm_enable_lbrv(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -802,6 +813,10 @@ static void svm_enable_lbrv(struct kvm_vcpu *vcpu)
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTBRANCHTOIP, 1, 1);
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTFROMIP, 1, 1);
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTTOIP, 1, 1);
/* Move the LBR msrs to the vmcb02 so that the guest can see them. */
if (is_guest_mode(vcpu))
svm_copy_lbrs(svm->vmcb, svm->vmcb01.ptr);
}
static void svm_disable_lbrv(struct kvm_vcpu *vcpu)
@@ -813,6 +828,63 @@ static void svm_disable_lbrv(struct kvm_vcpu *vcpu)
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTBRANCHTOIP, 0, 0);
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTFROMIP, 0, 0);
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTTOIP, 0, 0);
/*
* Move the LBR msrs back to the vmcb01 to avoid copying them
* on nested guest entries.
*/
if (is_guest_mode(vcpu))
svm_copy_lbrs(svm->vmcb01.ptr, svm->vmcb);
}
static int svm_get_lbr_msr(struct vcpu_svm *svm, u32 index)
{
/*
* If the LBR virtualization is disabled, the LBR msrs are always
* kept in the vmcb01 to avoid copying them on nested guest entries.
*
* If nested, and the LBR virtualization is enabled/disabled, the msrs
* are moved between the vmcb01 and vmcb02 as needed.
*/
struct vmcb *vmcb =
(svm->vmcb->control.virt_ext & LBR_CTL_ENABLE_MASK) ?
svm->vmcb : svm->vmcb01.ptr;
switch (index) {
case MSR_IA32_DEBUGCTLMSR:
return vmcb->save.dbgctl;
case MSR_IA32_LASTBRANCHFROMIP:
return vmcb->save.br_from;
case MSR_IA32_LASTBRANCHTOIP:
return vmcb->save.br_to;
case MSR_IA32_LASTINTFROMIP:
return vmcb->save.last_excp_from;
case MSR_IA32_LASTINTTOIP:
return vmcb->save.last_excp_to;
default:
KVM_BUG(false, svm->vcpu.kvm,
"%s: Unknown MSR 0x%x", __func__, index);
return 0;
}
}
void svm_update_lbrv(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
bool enable_lbrv = svm_get_lbr_msr(svm, MSR_IA32_DEBUGCTLMSR) &
DEBUGCTLMSR_LBR;
bool current_enable_lbrv = !!(svm->vmcb->control.virt_ext &
LBR_CTL_ENABLE_MASK);
if (enable_lbrv == current_enable_lbrv)
return;
if (enable_lbrv)
svm_enable_lbrv(vcpu);
else
svm_disable_lbrv(vcpu);
}
void disable_nmi_singlestep(struct vcpu_svm *svm)
@@ -2581,25 +2653,12 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_TSC_AUX:
msr_info->data = svm->tsc_aux;
break;
/*
* Nobody will change the following 5 values in the VMCB so we can
* safely return them on rdmsr. They will always be 0 until LBRV is
* implemented.
*/
case MSR_IA32_DEBUGCTLMSR:
msr_info->data = svm->vmcb->save.dbgctl;
break;
case MSR_IA32_LASTBRANCHFROMIP:
msr_info->data = svm->vmcb->save.br_from;
break;
case MSR_IA32_LASTBRANCHTOIP:
msr_info->data = svm->vmcb->save.br_to;
break;
case MSR_IA32_LASTINTFROMIP:
msr_info->data = svm->vmcb->save.last_excp_from;
break;
case MSR_IA32_LASTINTTOIP:
msr_info->data = svm->vmcb->save.last_excp_to;
msr_info->data = svm_get_lbr_msr(svm, msr_info->index);
break;
case MSR_VM_HSAVE_PA:
msr_info->data = svm->nested.hsave_msr;
@@ -2845,12 +2904,13 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
if (data & DEBUGCTL_RESERVED_BITS)
return 1;
if (svm->vmcb->control.virt_ext & LBR_CTL_ENABLE_MASK)
svm->vmcb->save.dbgctl = data;
vmcb_mark_dirty(svm->vmcb, VMCB_LBR);
if (data & (1ULL<<0))
svm_enable_lbrv(vcpu);
else
svm_disable_lbrv(vcpu);
svm->vmcb01.ptr->save.dbgctl = data;
svm_update_lbrv(vcpu);
break;
case MSR_VM_HSAVE_PA:
/*

2
arch/x86/kvm/svm/svm.h
View File

@@ -492,6 +492,8 @@ u32 svm_msrpm_offset(u32 msr);
u32 *svm_vcpu_alloc_msrpm(void);
void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm);
void svm_vcpu_free_msrpm(u32 *msrpm);
void svm_copy_lbrs(struct vmcb *to_vmcb, struct vmcb *from_vmcb);
void svm_update_lbrv(struct kvm_vcpu *vcpu);
int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer);
void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);