[Xen-changelog] [xen master] x86/ucode/intel: Remove one CPUID from collect_cpu_info()

[patchbot@xxxxxxx]

commit c81fb4e4a35cbee4f373387c4ed527676f6dc4b1
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Apr 1 15:52:43 2020 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Apr 3 20:11:46 2020 +0100

    x86/ucode/intel: Remove one CPUID from collect_cpu_info()
    
    The CPUID instruction is expensive.  No point executing it twice when once
    will do fine.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/cpu/microcode/intel.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/xen/arch/x86/cpu/microcode/intel.c 
b/xen/arch/x86/cpu/microcode/intel.c
index 72bd1ad0bc..f1e64e188b 100644
--- a/xen/arch/x86/cpu/microcode/intel.c
+++ b/xen/arch/x86/cpu/microcode/intel.c
@@ -121,14 +121,12 @@ static int collect_cpu_info(struct cpu_signature *csig)
 
     memset(csig, 0, sizeof(*csig));
 
-    csig->sig = cpuid_eax(0x00000001);
-
     rdmsrl(MSR_IA32_PLATFORM_ID, msr_content);
     csig->pf = 1 << ((msr_content >> 50) & 7);
 
     wrmsrl(MSR_IA32_UCODE_REV, 0x0ULL);
     /* As documented in the SDM: Do a CPUID 1 here */
-    cpuid_eax(1);
+    csig->sig = cpuid_eax(1);
 
     /* get the current revision from MSR 0x8B */
     rdmsrl(MSR_IA32_UCODE_REV, msr_content);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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