linux-kernel - [PATCH v11 02/23] KVM: x86: Add kvm_msr

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Message-ID: <20250704085027.182163-3-chao.gao@intel.com>
Date: Fri,  4 Jul 2025 01:49:33 -0700
From: Chao Gao <chao.gao@...el.com>
To: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	x86@...nel.org,
	seanjc@...gle.com,
	pbonzini@...hat.com,
	dave.hansen@...el.com
Cc: rick.p.edgecombe@...el.com,
	mlevitsk@...hat.com,
	john.allen@....com,
	weijiang.yang@...el.com,
	minipli@...ecurity.net,
	xin@...or.com,
	Chao Gao <chao.gao@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v11 02/23] KVM: x86: Add kvm_msr_{read,write}() helpers

From: Yang Weijiang <weijiang.yang@...el.com>

Wrap __kvm_{get,set}_msr() into two new helpers for KVM usage and use the
helpers to replace existing usage of the raw functions.
kvm_msr_{read,write}() are KVM-internal helpers, i.e. used when KVM needs
to get/set a MSR value for emulating CPU behavior, i.e., host_initiated ==
%true in the helpers.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
Signed-off-by: Chao Gao <chao.gao@...el.com>
Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/include/asm/kvm_host.h |  3 ++-
 arch/x86/kvm/cpuid.c            |  2 +-
 arch/x86/kvm/x86.c              | 16 +++++++++++++---
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1f3f8601747f..e07a03dbce6a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2152,9 +2152,10 @@ void kvm_enable_efer_bits(u64);
 bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
 int kvm_emulate_msr_read_with_filter(struct kvm_vcpu *vcpu, u32 index, u64 *data);
 int kvm_emulate_msr_write_with_filter(struct kvm_vcpu *vcpu, u32 index, u64 data);
-int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data, bool host_initiated);
 int kvm_emulate_msr_read(struct kvm_vcpu *vcpu, u32 index, u64 *data);
 int kvm_emulate_msr_write(struct kvm_vcpu *vcpu, u32 index, u64 data);
+int kvm_msr_read(struct kvm_vcpu *vcpu, u32 index, u64 *data);
+int kvm_msr_write(struct kvm_vcpu *vcpu, u32 index, u64 data);
 int kvm_emulate_rdmsr(struct kvm_vcpu *vcpu);
 int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu);
 int kvm_emulate_as_nop(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index b2d006756e02..9db246671885 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1992,7 +1992,7 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
 		if (function == 7 && index == 0) {
 			u64 data;
 			if ((*ebx & (feature_bit(RTM) | feature_bit(HLE))) &&
-			    !__kvm_get_msr(vcpu, MSR_IA32_TSX_CTRL, &data, true) &&
+			    !kvm_msr_read(vcpu, MSR_IA32_TSX_CTRL, &data) &&
 			    (data & TSX_CTRL_CPUID_CLEAR))
 				*ebx &= ~(feature_bit(RTM) | feature_bit(HLE));
 		} else if (function == 0x80000007) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 11d84075cd14..51b37492142c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1895,8 +1895,8 @@ static int kvm_set_msr_ignored_check(struct kvm_vcpu *vcpu,
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
-		  bool host_initiated)
+static int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
+			 bool host_initiated)
 {
 	struct msr_data msr;
 	int ret;
@@ -1922,6 +1922,16 @@ int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
 	return ret;
 }
 
+int kvm_msr_write(struct kvm_vcpu *vcpu, u32 index, u64 data)
+{
+	return __kvm_set_msr(vcpu, index, data, true);
+}
+
+int kvm_msr_read(struct kvm_vcpu *vcpu, u32 index, u64 *data)
+{
+	return __kvm_get_msr(vcpu, index, data, true);
+}
+
 static int kvm_get_msr_ignored_check(struct kvm_vcpu *vcpu,
 				     u32 index, u64 *data, bool host_initiated)
 {
@@ -12591,7 +12601,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 						  MSR_IA32_MISC_ENABLE_BTS_UNAVAIL;
 
 		__kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
-		__kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
+		kvm_msr_write(vcpu, MSR_IA32_XSS, 0);
 	}
 
 	/* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
-- 
2.47.1