linux-kernel - [PATCH v5 2/7] KVM: VMX: Add proper cache tracking for PKRS

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Date:   Wed, 11 Aug 2021 18:11:21 +0800
From:   Chenyi Qiang <chenyi.qiang@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Xiaoyao Li <xiaoyao.li@...el.com>
Cc:     Chenyi Qiang <chenyi.qiang@...el.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v5 2/7] KVM: VMX: Add proper cache tracking for PKRS

Add PKRS caching into the standard register caching mechanism in order
to take advantage of the availability checks provided by regs_avail.

This is because vcpu->arch.pkrs will be rarely acceesed by KVM, only in
the case of host userspace MSR reads and GVA->GPA translation in
following patches. It is unnecessary to keep it up-to-date at all times.

Signed-off-by: Chenyi Qiang <chenyi.qiang@...el.com>
---
 arch/x86/include/asm/kvm_host.h | 2 ++
 arch/x86/kvm/kvm_cache_regs.h   | 7 +++++++
 arch/x86/kvm/vmx/vmx.c          | 4 ++++
 arch/x86/kvm/vmx/vmx.h          | 3 ++-
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 974cbfb1eefe..c2bcb88781b3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -173,6 +173,7 @@ enum kvm_reg {
 	VCPU_EXREG_SEGMENTS,
 	VCPU_EXREG_EXIT_INFO_1,
 	VCPU_EXREG_EXIT_INFO_2,
+	VCPU_EXREG_PKRS,
 };
 
 enum {
@@ -620,6 +621,7 @@ struct kvm_vcpu_arch {
 	unsigned long cr8;
 	u32 host_pkru;
 	u32 pkru;
+	u32 pkrs;
 	u32 hflags;
 	u64 efer;
 	u64 apic_base;
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index 90e1ffdc05b7..da014b1be874 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -171,6 +171,13 @@ static inline u64 kvm_read_edx_eax(struct kvm_vcpu *vcpu)
 		| ((u64)(kvm_rdx_read(vcpu) & -1u) << 32);
 }
 
+static inline ulong kvm_read_pkrs(struct kvm_vcpu *vcpu)
+{
+	if (!kvm_register_is_available(vcpu, VCPU_EXREG_PKRS))
+		static_call(kvm_x86_cache_reg)(vcpu, VCPU_EXREG_PKRS);
+	return vcpu->arch.pkrs;
+}
+
 static inline void enter_guest_mode(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.hflags |= HF_GUEST_MASK;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 927a552393b9..bf911029aa35 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2273,6 +2273,10 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
 		vcpu->arch.cr4 &= ~guest_owned_bits;
 		vcpu->arch.cr4 |= vmcs_readl(GUEST_CR4) & guest_owned_bits;
 		break;
+	case VCPU_EXREG_PKRS:
+		if (kvm_cpu_cap_has(X86_FEATURE_PKS))
+			vcpu->arch.pkrs = vmcs_read64(GUEST_IA32_PKRS);
+		break;
 	default:
 		WARN_ON_ONCE(1);
 		break;
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index db88ed4f2121..18039eb6efb0 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -447,7 +447,8 @@ static inline void vmx_register_cache_reset(struct kvm_vcpu *vcpu)
 				  | (1 << VCPU_EXREG_CR3)
 				  | (1 << VCPU_EXREG_CR4)
 				  | (1 << VCPU_EXREG_EXIT_INFO_1)
-				  | (1 << VCPU_EXREG_EXIT_INFO_2));
+				  | (1 << VCPU_EXREG_EXIT_INFO_2)
+				  | (1 << VCPU_EXREG_PKRS));
 	vcpu->arch.regs_dirty = 0;
 }
 
-- 
2.17.1