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

Message ID 20200201185218.24473-10-sean.j.christopherson@intel.com
State New, archived
Headers show
Series KVM: x86: Introduce KVM cpu caps | expand

Commit Message

Sean Christopherson Feb. 1, 2020, 6:51 p.m. UTC
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@intel.com>
---
 arch/x86/kvm/cpuid.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Vitaly Kuznetsov Feb. 7, 2020, 3:56 p.m. UTC | #1
Sean Christopherson <sean.j.christopherson@intel.com> writes:

> 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@intel.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;

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
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Patch

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;