linux-kernel - [PATCH 26/28] KVM: SVM: Return -EINVAL instead of MSR

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Message-ID: <20250529234013.3826933-27-seanjc@google.com>
Date: Thu, 29 May 2025 16:40:11 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Borislav Petkov <bp@...en8.de>, Xin Li <xin@...or.com>, Chao Gao <chao.gao@...el.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: [PATCH 26/28] KVM: SVM: Return -EINVAL instead of MSR_INVALID to
 signal out-of-range MSR

Return -EINVAL instead of MSR_INVALID from svm_msrpm_offset() to indicate
that the MSR isn't covered by one of the (currently) three MSRPM ranges,
and delete the MSR_INVALID macro now that all users are gone.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/nested.c | 14 +++++++-------
 arch/x86/kvm/svm/svm.h    |  2 --
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index a4e98ada732b..60f62cddd291 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -191,14 +191,14 @@ static int nested_svm_nr_msrpm_merge_offsets __ro_after_init;
 	case SVM_MSRPM_FIRST_MSR(range_nr) ... SVM_MSRPM_LAST_MSR(range_nr):	\
 		return SVM_MSRPM_BYTE_NR(range_nr, msr);
 
-static u32 svm_msrpm_offset(u32 msr)
+static int svm_msrpm_offset(u32 msr)
 {
 	switch (msr) {
 	SVM_BUILD_MSR_BYTE_NR_CASE(0, msr)
 	SVM_BUILD_MSR_BYTE_NR_CASE(1, msr)
 	SVM_BUILD_MSR_BYTE_NR_CASE(2, msr)
 	default:
-		return MSR_INVALID;
+		return -EINVAL;
 	}
 }
 
@@ -228,9 +228,9 @@ int __init nested_svm_init_msrpm_merge_offsets(void)
 	int i, j;
 
 	for (i = 0; i < ARRAY_SIZE(merge_msrs); i++) {
-		u32 offset = svm_msrpm_offset(merge_msrs[i]);
+		int offset = svm_msrpm_offset(merge_msrs[i]);
 
-		if (WARN_ON(offset == MSR_INVALID))
+		if (WARN_ON(offset < 0))
 			return -EIO;
 
 		/*
@@ -1357,9 +1357,9 @@ void svm_leave_nested(struct kvm_vcpu *vcpu)
 
 static int nested_svm_exit_handled_msr(struct vcpu_svm *svm)
 {
-	u32 offset, msr;
-	int write;
+	int offset, write;
 	u8 value;
+	u32 msr;
 
 	if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT)))
 		return NESTED_EXIT_HOST;
@@ -1368,7 +1368,7 @@ static int nested_svm_exit_handled_msr(struct vcpu_svm *svm)
 	offset = svm_msrpm_offset(msr);
 	write  = svm->vmcb->control.exit_info_1 & 1;
 
-	if (offset == MSR_INVALID)
+	if (offset < 0)
 		return NESTED_EXIT_DONE;
 
 	if (kvm_vcpu_read_guest(&svm->vcpu, svm->nested.ctl.msrpm_base_pa + offset,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 155b6089fcd2..27c722fd766e 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -677,8 +677,6 @@ BUILD_SVM_MSR_BITMAP_HELPERS(bool, test, test)
 BUILD_SVM_MSR_BITMAP_HELPERS(void, clear, __clear)
 BUILD_SVM_MSR_BITMAP_HELPERS(void, set, __set)
 
-#define MSR_INVALID				0xffffffffU
-
 #define DEBUGCTL_RESERVED_BITS (~DEBUGCTLMSR_LBR)
 
 /* svm.c */
-- 
2.49.0.1204.g71687c7c1d-goog