[PATCH 01/10] KVM: x86: Save L1 TSC offset in 'struct kvm_vcpu_arch'

[Sean Christopherson]

Save L1's TSC offset in 'struct kvm_vcpu_arch' and drop the kvm_x86_ops
hook read_l1_tsc_offset().  This avoids a retpoline (when configured)
when reading L1's effective TSC, which is done at least once on every
VM-Exit.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopher...@intel.com>
---
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/svm/svm.c          | 11 -----------
 arch/x86/kvm/vmx/vmx.c          | 12 ------------
 arch/x86/kvm/x86.c              |  9 ++++-----
 4 files changed, 5 insertions(+), 29 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7cd68d1d0627..d71d1f38b7a0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -707,6 +707,7 @@ struct kvm_vcpu_arch {
                struct gfn_to_pfn_cache cache;
        } st;
 
+       u64 l1_tsc_offset;
        u64 tsc_offset;
        u64 last_guest_tsc;
        u64 last_host_tsc;
@@ -1166,7 +1167,6 @@ struct kvm_x86_ops {
 
        bool (*has_wbinvd_exit)(void);
 
-       u64 (*read_l1_tsc_offset)(struct kvm_vcpu *vcpu);
        /* Returns actual tsc_offset set in active VMCS */
        u64 (*write_l1_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
 
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 8f8fc65bfa3e..f40a43a288b9 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -954,16 +954,6 @@ 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 u64 svm_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
 {
        struct vcpu_svm *svm = to_svm(vcpu);
@@ -4068,7 +4058,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 
        .has_wbinvd_exit = svm_has_wbinvd_exit,
 
-       .read_l1_tsc_offset = svm_read_l1_tsc_offset,
        .write_l1_tsc_offset = svm_write_l1_tsc_offset,
 
        .load_mmu_pgd = svm_load_mmu_pgd,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d3d57b7a67bd..de18cd386bb1 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1723,17 +1723,6 @@ 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_OFFSETTING))
-               return vcpu->arch.tsc_offset - vmcs12->tsc_offset;
-
-       return vcpu->arch.tsc_offset;
-}
-
 static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
 {
        struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
@@ -7865,7 +7854,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 
        .has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,
 
-       .read_l1_tsc_offset = vmx_read_l1_tsc_offset,
        .write_l1_tsc_offset = vmx_write_l1_tsc_offset,
 
        .load_mmu_pgd = vmx_load_mmu_pgd,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 856b6fc2c2ba..8ec356ac1e6e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1918,7 +1918,7 @@ 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 = kvm_x86_ops.read_l1_tsc_offset(vcpu);
+       u64 curr_offset = vcpu->arch.l1_tsc_offset;
        vcpu->arch.ia32_tsc_adjust_msr += offset - curr_offset;
 }
 
@@ -1960,14 +1960,13 @@ 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)
 {
-       u64 tsc_offset = kvm_x86_ops.read_l1_tsc_offset(vcpu);
-
-       return tsc_offset + kvm_scale_tsc(vcpu, host_tsc);
+       return vcpu->arch.l1_tsc_offset + kvm_scale_tsc(vcpu, host_tsc);
 }
 EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);
 
 static void kvm_vcpu_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
 {
+       vcpu->arch.l1_tsc_offset = offset;
        vcpu->arch.tsc_offset = kvm_x86_ops.write_l1_tsc_offset(vcpu, offset);
 }
 
@@ -2092,7 +2091,7 @@ EXPORT_SYMBOL_GPL(kvm_write_tsc);
 static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu,
                                           s64 adjustment)
 {
-       u64 tsc_offset = kvm_x86_ops.read_l1_tsc_offset(vcpu);
+       u64 tsc_offset = vcpu->arch.l1_tsc_offset;
        kvm_vcpu_write_tsc_offset(vcpu, tsc_offset + adjustment);
 }
 
-- 
2.26.0