[PATCH] KVM: x86: Fix implicit enum conversion goof in scattered reverse CPUID code

From: Sean Christopherson
Date: Tue Apr 20 2021 - 21:09:00 EST


Take "enum kvm_only_cpuid_leafs" in scattered specific CPUID helpers
(which is obvious in hindsight), and use "unsigned int" for leafs that
can be the kernel's standard "enum cpuid_leaf" or the aforementioned
KVM-only variant. Loss of the enum params is a bit disapponting, but
gcc obviously isn't providing any extra sanity checks, and the various
BUILD_BUG_ON() assertions ensure the input is in range.

This fixes implicit enum conversions that are detected by clang-11.

Fixes: 4e66c0cb79b7 ("KVM: x86: Add support for reverse CPUID lookup of scattered features")
Cc: Kai Huang <kai.huang@xxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---

Hopefully it's not too late to squash this...

arch/x86/kvm/cpuid.c | 5 +++--
arch/x86/kvm/cpuid.h | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 96e41e1a1bde..e9d644147bf5 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -365,7 +365,7 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
}

/* Mask kvm_cpu_caps for @leaf with the raw CPUID capabilities of this CPU. */
-static __always_inline void __kvm_cpu_cap_mask(enum cpuid_leafs leaf)
+static __always_inline void __kvm_cpu_cap_mask(unsigned int leaf)
{
const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32);
struct kvm_cpuid_entry2 entry;
@@ -378,7 +378,8 @@ static __always_inline void __kvm_cpu_cap_mask(enum cpuid_leafs leaf)
kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, cpuid.reg);
}

-static __always_inline void kvm_cpu_cap_init_scattered(enum cpuid_leafs leaf, u32 mask)
+static __always_inline
+void kvm_cpu_cap_init_scattered(enum kvm_only_cpuid_leafs leaf, u32 mask)
{
/* Use kvm_cpu_cap_mask for non-scattered leafs. */
BUILD_BUG_ON(leaf < NCAPINTS);
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index eeb4a3020e1b..7bb4504a2944 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -236,7 +236,7 @@ static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
}

static __always_inline void cpuid_entry_override(struct kvm_cpuid_entry2 *entry,
- enum cpuid_leafs leaf)
+ unsigned int leaf)
{
u32 *reg = cpuid_entry_get_reg(entry, leaf * 32);

--
2.31.1.368.gbe11c130af-goog