Commit 56ba77a4 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86: Save L1 TSC offset in 'struct kvm_vcpu_arch' 



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: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200502043234.12481-2-sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 1af1bb05

arch/x86/include/asm/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -708,6 +708,7 @@ 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;
@@ -1165,7 +1166,6 @@ 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);

arch/x86/kvm/svm/svm.c

+0 −11
Original line number Diff line number Diff line
@@ -951,16 +951,6 @@ 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);
@@ -4075,7 +4065,6 @@ 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,

arch/x86/kvm/vmx/vmx.c

+0 −12
Original line number Diff line number Diff line
@@ -1740,17 +1740,6 @@ 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);
@@ -7881,7 +7870,6 @@ 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,

arch/x86/kvm/x86.c

+4 −5
Original line number Diff line number Diff line
@@ -1910,7 +1910,7 @@ 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;

}
@@ -1952,14 +1952,13 @@ 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);

}
@@ -2084,7 +2083,7 @@ 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);

}

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