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X86/KVM: Properly update 'tsc_offset' to represent the running guest
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Update 'tsc_offset' on vmentry/vmexit of L2 guests to ensure that it always
captures the TSC_OFFSET of the running guest whether it is the L1 or L2
guest.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
[AMD changes, fix update_ia32_tsc_adjust_msr. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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KarimAllah Ahmed authored and Paolo Bonzini committed Apr 16, 2018
1 parent 4e1acd7 commit e79f245
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Showing 4 changed files with 56 additions and 22 deletions.
1 change: 1 addition & 0 deletions arch/x86/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1013,6 +1013,7 @@ struct kvm_x86_ops {

bool (*has_wbinvd_exit)(void);

u64 (*read_l1_tsc_offset)(struct kvm_vcpu *vcpu);
void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);

void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);
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17 changes: 16 additions & 1 deletion arch/x86/kvm/svm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1424,12 +1424,23 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type)
seg->base = 0;
}

static u64 svm_read_l1_tsc_offset(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);

if (is_guest_mode(vcpu))
return svm->nested.hsave->control.tsc_offset;

return vcpu->arch.tsc_offset;
}

static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
{
struct vcpu_svm *svm = to_svm(vcpu);
u64 g_tsc_offset = 0;

if (is_guest_mode(vcpu)) {
/* Write L1's TSC offset. */
g_tsc_offset = svm->vmcb->control.tsc_offset -
svm->nested.hsave->control.tsc_offset;
svm->nested.hsave->control.tsc_offset = offset;
Expand Down Expand Up @@ -3323,6 +3334,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
/* Restore the original control entries */
copy_vmcb_control_area(vmcb, hsave);

svm->vcpu.arch.tsc_offset = svm->vmcb->control.tsc_offset;
kvm_clear_exception_queue(&svm->vcpu);
kvm_clear_interrupt_queue(&svm->vcpu);

Expand Down Expand Up @@ -3483,10 +3495,12 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
/* We don't want to see VMMCALLs from a nested guest */
clr_intercept(svm, INTERCEPT_VMMCALL);

svm->vcpu.arch.tsc_offset += nested_vmcb->control.tsc_offset;
svm->vmcb->control.tsc_offset = svm->vcpu.arch.tsc_offset;

svm->vmcb->control.virt_ext = nested_vmcb->control.virt_ext;
svm->vmcb->control.int_vector = nested_vmcb->control.int_vector;
svm->vmcb->control.int_state = nested_vmcb->control.int_state;
svm->vmcb->control.tsc_offset += nested_vmcb->control.tsc_offset;
svm->vmcb->control.event_inj = nested_vmcb->control.event_inj;
svm->vmcb->control.event_inj_err = nested_vmcb->control.event_inj_err;

Expand Down Expand Up @@ -7102,6 +7116,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {

.has_wbinvd_exit = svm_has_wbinvd_exit,

.read_l1_tsc_offset = svm_read_l1_tsc_offset,
.write_tsc_offset = svm_write_tsc_offset,

.set_tdp_cr3 = set_tdp_cr3,
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54 changes: 35 additions & 19 deletions arch/x86/kvm/vmx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2874,6 +2874,17 @@ static void setup_msrs(struct vcpu_vmx *vmx)
vmx_update_msr_bitmap(&vmx->vcpu);
}

static u64 vmx_read_l1_tsc_offset(struct kvm_vcpu *vcpu)
{
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);

if (is_guest_mode(vcpu) &&
(vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING))
return vcpu->arch.tsc_offset - vmcs12->tsc_offset;

return vcpu->arch.tsc_offset;
}

/*
* reads and returns guest's timestamp counter "register"
* guest_tsc = (host_tsc * tsc multiplier) >> 48 + tsc_offset
Expand Down Expand Up @@ -11175,11 +11186,8 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
vmcs_write64(GUEST_IA32_PAT, vmx->vcpu.arch.pat);
}

if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
vmcs_write64(TSC_OFFSET,
vcpu->arch.tsc_offset + vmcs12->tsc_offset);
else
vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset);
vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset);

if (kvm_has_tsc_control)
decache_tsc_multiplier(vmx);

Expand Down Expand Up @@ -11427,6 +11435,7 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry)
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
u32 msr_entry_idx;
u32 exit_qual;
int r;

enter_guest_mode(vcpu);

Expand All @@ -11436,26 +11445,21 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry)
vmx_switch_vmcs(vcpu, &vmx->nested.vmcs02);
vmx_segment_cache_clear(vmx);

if (prepare_vmcs02(vcpu, vmcs12, from_vmentry, &exit_qual)) {
leave_guest_mode(vcpu);
vmx_switch_vmcs(vcpu, &vmx->vmcs01);
nested_vmx_entry_failure(vcpu, vmcs12,
EXIT_REASON_INVALID_STATE, exit_qual);
return 1;
}
if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
vcpu->arch.tsc_offset += vmcs12->tsc_offset;

r = EXIT_REASON_INVALID_STATE;
if (prepare_vmcs02(vcpu, vmcs12, from_vmentry, &exit_qual))
goto fail;

nested_get_vmcs12_pages(vcpu, vmcs12);

r = EXIT_REASON_MSR_LOAD_FAIL;
msr_entry_idx = nested_vmx_load_msr(vcpu,
vmcs12->vm_entry_msr_load_addr,
vmcs12->vm_entry_msr_load_count);
if (msr_entry_idx) {
leave_guest_mode(vcpu);
vmx_switch_vmcs(vcpu, &vmx->vmcs01);
nested_vmx_entry_failure(vcpu, vmcs12,
EXIT_REASON_MSR_LOAD_FAIL, msr_entry_idx);
return 1;
}
if (msr_entry_idx)
goto fail;

/*
* Note no nested_vmx_succeed or nested_vmx_fail here. At this point
Expand All @@ -11464,6 +11468,14 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry)
* the success flag) when L2 exits (see nested_vmx_vmexit()).
*/
return 0;

fail:
if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
vcpu->arch.tsc_offset -= vmcs12->tsc_offset;
leave_guest_mode(vcpu);
vmx_switch_vmcs(vcpu, &vmx->vmcs01);
nested_vmx_entry_failure(vcpu, vmcs12, r, exit_qual);
return 1;
}

/*
Expand Down Expand Up @@ -12035,6 +12047,9 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,

leave_guest_mode(vcpu);

if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
vcpu->arch.tsc_offset -= vmcs12->tsc_offset;

if (likely(!vmx->fail)) {
if (exit_reason == -1)
sync_vmcs12(vcpu, vmcs12);
Expand Down Expand Up @@ -12725,6 +12740,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {

.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,

.read_l1_tsc_offset = vmx_read_l1_tsc_offset,
.write_tsc_offset = vmx_write_tsc_offset,

.set_tdp_cr3 = vmx_set_cr3,
Expand Down
6 changes: 4 additions & 2 deletions arch/x86/kvm/x86.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1490,7 +1490,7 @@ static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)

static void update_ia32_tsc_adjust_msr(struct kvm_vcpu *vcpu, s64 offset)
{
u64 curr_offset = vcpu->arch.tsc_offset;
u64 curr_offset = kvm_x86_ops->read_l1_tsc_offset(vcpu);
vcpu->arch.ia32_tsc_adjust_msr += offset - curr_offset;
}

Expand Down Expand Up @@ -1532,7 +1532,9 @@ static u64 kvm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)

u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
{
return vcpu->arch.tsc_offset + kvm_scale_tsc(vcpu, host_tsc);
u64 tsc_offset = kvm_x86_ops->read_l1_tsc_offset(vcpu);

return tsc_offset + kvm_scale_tsc(vcpu, host_tsc);
}
EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);

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