KVM: SVM: Return -EINVAL instead of MSR_INVALID to signal out-of-range MSR

Return -EINVAL instead of MSR_INVALID from svm_msrpm_bit_nr() 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.

Link: https://lore.kernel.org/r/20250610225737.156318-29-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

arch/x86/kvm/svm/nested.c

@@ -223,10 +223,10 @@ int __init nested_svm_init_msrpm_merge_offsets(void)
 	int i, j;
 
 	for (i = 0; i < ARRAY_SIZE(merge_msrs); i++) {
-		u32 bit_nr = svm_msrpm_bit_nr(merge_msrs[i]);
+		int bit_nr = svm_msrpm_bit_nr(merge_msrs[i]);
 		u32 offset;
 
-		if (WARN_ON(bit_nr == MSR_INVALID))
+		if (WARN_ON(bit_nr < 0))
 			return -EIO;
 
 		/*
@@ -1354,9 +1354,9 @@ void svm_leave_nested(struct kvm_vcpu *vcpu)
 static int nested_svm_exit_handled_msr(struct vcpu_svm *svm)
 {
 	gpa_t base = svm->nested.ctl.msrpm_base_pa;
-	u32 msr, bit_nr;
+	int write, bit_nr;
 	u8 value, mask;
-	int write;
+	u32 msr;
 
 	if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT)))
 		return NESTED_EXIT_HOST;
@@ -1365,7 +1365,7 @@ static int nested_svm_exit_handled_msr(struct vcpu_svm *svm)
 	bit_nr = svm_msrpm_bit_nr(msr);
 	write  = svm->vmcb->control.exit_info_1 & 1;
 
-	if (bit_nr == MSR_INVALID)
+	if (bit_nr < 0)
 		return NESTED_EXIT_DONE;
 
 	if (kvm_vcpu_read_guest(&svm->vcpu, base + bit_nr / BITS_PER_BYTE,

arch/x86/kvm/svm/svm.h

@@ -619,9 +619,7 @@ static inline void svm_vmgexit_no_action(struct vcpu_svm *svm, u64 data)
 static_assert(SVM_MSRS_PER_RANGE == 8192);
 #define SVM_MSRPM_OFFSET_MASK (SVM_MSRS_PER_RANGE - 1)
 
-#define MSR_INVALID				0xffffffffU
-
-static __always_inline u32 svm_msrpm_bit_nr(u32 msr)
+static __always_inline int svm_msrpm_bit_nr(u32 msr)
 {
 	int range_nr;
 
@@ -636,7 +634,7 @@ static __always_inline u32 svm_msrpm_bit_nr(u32 msr)
 		range_nr = 2;
 		break;
 	default:
-		return MSR_INVALID;
+		return -EINVAL;
 	}
 
 	return range_nr * SVM_MSRPM_BYTES_PER_RANGE * BITS_PER_BYTE +
@@ -647,10 +645,10 @@ static __always_inline u32 svm_msrpm_bit_nr(u32 msr)
 static inline rtype svm_##action##_msr_bitmap_##access(unsigned long *bitmap,	\
 						       u32 msr)			\
 {										\
-	u32 bit_nr;								\
+	int bit_nr;								\
 										\
 	bit_nr = svm_msrpm_bit_nr(msr);						\
-	if (bit_nr == MSR_INVALID)								\
+	if (bit_nr < 0)								\
 		return (rtype)true;						\
 										\
 	return bitop##_bit(bit_nr + bit_rw, bitmap);				\