linux-kernel - [PATCH 09/61] KVM: x86: Refactor CPUID 0xD.N sub-leaf entry creation

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Date:   Sat,  1 Feb 2020 10:51:26 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 09/61] KVM: x86: Refactor CPUID 0xD.N sub-leaf entry creation

Increment the number of CPUID entries immediately after do_host_cpuid()
in preparation for moving the logic into do_host_cpuid().  Handle the
rare/impossible case of encountering a bogus sub-leaf by decrementing
the number entries on failure.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/cpuid.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 424dde41cb5d..6e1685a16cca 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -677,6 +677,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 				goto out;
 
 			do_host_cpuid(&entry[i], function, idx);
+			++*nent;
 
 			/*
 			 * The @supported check above should have filtered out
@@ -685,12 +686,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 			 * reach this point, and they should have a non-zero
 			 * save state size.
 			 */
-			if (WARN_ON_ONCE(!entry[i].eax || (entry[i].ecx & 1)))
+			if (WARN_ON_ONCE(!entry[i].eax || (entry[i].ecx & 1))) {
+				--*nent;
 				continue;
+			}
 
 			entry[i].ecx = 0;
 			entry[i].edx = 0;
-			++*nent;
 			++i;
 		}
 		break;
-- 
2.24.1