[PATCH v3 02/12] KVM: X86: Store L1's TSC scaling ratio in 'struct kvm_vcpu_arch'

Ilias Stamatis
2021-05-21T10:26:49Z

Store L1's scaling ratio in the kvm_vcpu_arch struct like we already do
for L1's TSC offset. This allows for easy save/restore when we enter and
then exit the nested guest.

Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
---
arch/x86/include/asm/kvm_host.h | 5 +++--
arch/x86/kvm/vmx/vmx.c | 4 ++--
arch/x86/kvm/x86.c | 6 ++++--
3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 55efbacfc244..7dfc609eacd6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -707,7 +707,7 @@ struct kvm_vcpu_arch {
} st;

u64 l1_tsc_offset;
- u64 tsc_offset;
+ u64 tsc_offset; /* current tsc offset */
u64 last_guest_tsc;
u64 last_host_tsc;
u64 tsc_offset_adjustment;
@@ -721,7 +721,8 @@ struct kvm_vcpu_arch {
u32 virtual_tsc_khz;
s64 ia32_tsc_adjust_msr;
u64 msr_ia32_power_ctl;
- u64 tsc_scaling_ratio;
+ u64 l1_tsc_scaling_ratio;
+ u64 tsc_scaling_ratio; /* current scaling ratio */

atomic_t nmi_queued; /* unprocessed asynchronous NMIs */
unsigned nmi_pending; /* NMI queued after currently running handler */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4bceb5ca3a89..3e4dda8177bb 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7453,10 +7453,10 @@ static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc,
delta_tsc = 0;

/* Convert to host delta tsc if tsc scaling is enabled */
- if (vcpu->arch.tsc_scaling_ratio != kvm_default_tsc_scaling_ratio &&
+ if (vcpu->arch.l1_tsc_scaling_ratio != kvm_default_tsc_scaling_ratio &&
delta_tsc && u64_shl_div_u64(delta_tsc,
kvm_tsc_scaling_ratio_frac_bits,
- vcpu->arch.tsc_scaling_ratio, &delta_tsc))
+ vcpu->arch.l1_tsc_scaling_ratio, &delta_tsc))
return -ERANGE;

/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bbc4e04e67ad..6ab95ac188a5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2185,6 +2185,7 @@ static int set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)

/* Guest TSC same frequency as host TSC? */
if (!scale) {
+ vcpu->arch.l1_tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
vcpu->arch.tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
return 0;
}
@@ -2211,7 +2212,7 @@ static int set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
return -1;
}

- vcpu->arch.tsc_scaling_ratio = ratio;
+ vcpu->arch.l1_tsc_scaling_ratio = vcpu->arch.tsc_scaling_ratio = ratio;
return 0;
}

@@ -2223,6 +2224,7 @@ static int kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz)
/* tsc_khz can be zero if TSC calibration fails */
if (user_tsc_khz == 0) {
/* set tsc_scaling_ratio to a safe value */
+ vcpu->arch.l1_tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
vcpu->arch.tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
return -1;
}
@@ -2459,7 +2461,7 @@ static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu,

static inline void adjust_tsc_offset_host(struct kvm_vcpu *vcpu, s64 adjustment)
{
- if (vcpu->arch.tsc_scaling_ratio != kvm_default_tsc_scaling_ratio)
+ if (vcpu->arch.l1_tsc_scaling_ratio != kvm_default_tsc_scaling_ratio)
WARN_ON(adjustment < 0);
adjustment = kvm_scale_tsc(vcpu, (u64) adjustment);
adjust_tsc_offset_guest(vcpu, adjustment);
--
2.17.1