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Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Tue, 20 Apr 2021 18:08:50 -0700
Message-Id: <20210421010850.3009718-1-seanjc@google.com>
Mime-Version: 1.0
Subject: [PATCH] KVM: x86: Fix implicit enum conversion goof in scattered
 reverse CPUID code
From:   Sean Christopherson <seanjc@google.com>
To:     Paolo Bonzini <pbonzini@redhat.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org,
        Kai Huang <kai.huang@intel.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---

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