2023-10-02 22:11:27

by Thomas Gleixner

Subject: [patch V4 14/30] x86/microcode/amd: Read revision from hardware in collect_cpu_info_amd()

Prepare to decrapify the core initialization logic which invokes
microcode_ops::apply_microcode() several times just to set
cpu_data::microcode.

Signed-off-by: Thomas Gleixner <[email protected]>
---
V2: New patch
---
arch/x86/kernel/cpu/microcode/amd.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -634,12 +634,12 @@ void reload_ucode_amd(unsigned int cpu)

static int collect_cpu_info_amd(int cpu, struct cpu_signature *csig)
{
- struct cpuinfo_x86 *c = &cpu_data(cpu);
struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
+ u32 dummy __always_unused;
struct ucode_patch *p;

csig->sig = cpuid_eax(0x00000001);
- csig->rev = c->microcode;
+ rdmsr(MSR_AMD64_PATCH_LEVEL, csig->rev, dummy);

/*
* a patch could have been loaded early, set uci->mc so that

2023-10-04 08:33:12

by Borislav Petkov

Subject: Re: [patch V4 14/30] x86/microcode/amd: Read revision from hardware in collect_cpu_info_amd()

On Mon, Oct 02, 2023 at 01:59:51PM +0200, Thomas Gleixner wrote:
> Prepare to decrapify the core initialization logic which invokes
> microcode_ops::apply_microcode() several times just to set
> cpu_data::microcode.
>
> Signed-off-by: Thomas Gleixner <[email protected]>
> ---
> V2: New patch
> ---
> arch/x86/kernel/cpu/microcode/amd.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- a/arch/x86/kernel/cpu/microcode/amd.c
> +++ b/arch/x86/kernel/cpu/microcode/amd.c
> @@ -634,12 +634,12 @@ void reload_ucode_amd(unsigned int cpu)
>
> static int collect_cpu_info_amd(int cpu, struct cpu_signature *csig)
> {
> - struct cpuinfo_x86 *c = &cpu_data(cpu);
> struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
> + u32 dummy __always_unused;
> struct ucode_patch *p;
>
> csig->sig = cpuid_eax(0x00000001);
> - csig->rev = c->microcode;
> + rdmsr(MSR_AMD64_PATCH_LEVEL, csig->rev, dummy);
>
> /*
> * a patch could have been loaded early, set uci->mc so that

Skipping that one as the rev needs to be read on the respective CPU for
mixed silicon steppings on AMD.

--
Regards/Gruss,
Boris.

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