linux-kernel - [PATCH v2 05/10] KVM: X86: Add functions for retrieving L2 TSC fields from common code

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Date:   Wed, 12 May 2021 16:09:40 +0100
From:   Ilias Stamatis <ilstam@...zon.com>
To:     <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <pbonzini@...hat.com>
CC:     <mlevitsk@...hat.com>, <seanjc@...gle.com>, <vkuznets@...hat.com>,
        <wanpengli@...cent.com>, <jmattson@...gle.com>, <joro@...tes.org>,
        <zamsden@...il.com>, <mtosatti@...hat.com>, <dwmw@...zon.co.uk>,
        <ilstam@...zon.com>
Subject: [PATCH v2 05/10] KVM: X86: Add functions for retrieving L2 TSC fields from common code

In order to implement as much of the nested TSC scaling logic as
possible in common code, we need these vendor callbacks for retrieving
the TSC offset and the TSC multiplier that L1 has set for L2.

Signed-off-by: Ilias Stamatis <ilstam@...zon.com>
---
 arch/x86/include/asm/kvm-x86-ops.h |  2 ++
 arch/x86/include/asm/kvm_host.h    |  2 ++
 arch/x86/kvm/svm/svm.c             | 14 ++++++++++++++
 arch/x86/kvm/vmx/vmx.c             | 25 +++++++++++++++++++++++++
 4 files changed, 43 insertions(+)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 323641097f63..2063616fba1c 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -87,6 +87,8 @@ KVM_X86_OP(set_identity_map_addr)
 KVM_X86_OP(get_mt_mask)
 KVM_X86_OP(load_mmu_pgd)
 KVM_X86_OP_NULL(has_wbinvd_exit)
+KVM_X86_OP(get_l2_tsc_offset)
+KVM_X86_OP(get_l2_tsc_multiplier)
 KVM_X86_OP(write_l1_tsc_offset)
 KVM_X86_OP(get_exit_info)
 KVM_X86_OP(check_intercept)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index be59197e5eb7..4c4a3fefff57 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1305,6 +1305,8 @@ struct kvm_x86_ops {
 
 	bool (*has_wbinvd_exit)(void);
 
+	u64 (*get_l2_tsc_offset)(struct kvm_vcpu *vcpu);
+	u64 (*get_l2_tsc_multiplier)(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 dfa351e605de..679b2fc1a3f9 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1082,6 +1082,18 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type)
 	seg->base = 0;
 }
 
+static u64 svm_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_svm *svm = to_svm(vcpu);
+
+	return svm->nested.ctl.tsc_offset;
+}
+
+static u64 svm_get_l2_tsc_multiplier(struct kvm_vcpu *vcpu)
+{
+	return kvm_default_tsc_scaling_ratio;
+}
+
 static u64 svm_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -4526,6 +4538,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 
 	.has_wbinvd_exit = svm_has_wbinvd_exit,
 
+	.get_l2_tsc_offset = svm_get_l2_tsc_offset,
+	.get_l2_tsc_multiplier = svm_get_l2_tsc_multiplier,
 	.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 4bceb5ca3a89..575e13bddda8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1787,6 +1787,29 @@ static void setup_msrs(struct vcpu_vmx *vmx)
 	vmx->guest_uret_msrs_loaded = false;
 }
 
+static u64 vmx_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
+{
+	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+	u64 offset = 0;
+
+	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING)
+		offset = vmcs12->tsc_offset;
+
+	return offset;
+}
+
+static u64 vmx_get_l2_tsc_multiplier(struct kvm_vcpu *vcpu)
+{
+	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+	u64 multiplier = kvm_default_tsc_scaling_ratio;
+
+	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING &&
+	    vmcs12->secondary_vm_exec_control & SECONDARY_EXEC_TSC_SCALING)
+		multiplier = vmcs12->tsc_multiplier;
+
+	return multiplier;
+}
+
 static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
 {
 	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
@@ -7700,6 +7723,8 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 
 	.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,
 
+	.get_l2_tsc_offset = vmx_get_l2_tsc_offset,
+	.get_l2_tsc_multiplier = vmx_get_l2_tsc_multiplier,
 	.write_l1_tsc_offset = vmx_write_l1_tsc_offset,
 
 	.load_mmu_pgd = vmx_load_mmu_pgd,
-- 
2.17.1