* [PATCH] x86/mtrr: Check if fixed-range MTRR exists in `mtrr_save_fixed_ranges`
@ 2025-05-09 8:56 Jiaqing Zhao
2025-05-09 10:44 ` Borislav Petkov
0 siblings, 1 reply; 2+ messages in thread
From: Jiaqing Zhao @ 2025-05-09 8:56 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
H. Peter Anvin, Bernhard Kaindl, Andi Kleen
Cc: Li Fei, Jiaqing Zhao, stable, linux-kernel
When suspending, `save_processor_state` calls `mtrr_save_fixed_ranges`
to save fixed-range MTRRs. On platforms without MTRR or fixed-range
MTRR support, accessing MTRR MSRs triggers unchecked MSR access error.
Make sure fixed-range MTRR is supported before access to prevent such
error.
Fixes: 3ebad5905609 ("[PATCH] x86: Save and restore the fixed-range MTRRs of the BSP when suspending")
Cc: stable@vger.kernel.org
Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
---
arch/x86/kernel/cpu/mtrr/generic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index e2c6b471d230..ca37b374d1b0 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -593,7 +593,7 @@ static void get_fixed_ranges(mtrr_type *frs)
void mtrr_save_fixed_ranges(void *info)
{
- if (boot_cpu_has(X86_FEATURE_MTRR))
+ if (boot_cpu_has(X86_FEATURE_MTRR) && mtrr_state.have_fixed)
get_fixed_ranges(mtrr_state.fixed_ranges);
}
--
2.43.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] x86/mtrr: Check if fixed-range MTRR exists in `mtrr_save_fixed_ranges`
2025-05-09 8:56 [PATCH] x86/mtrr: Check if fixed-range MTRR exists in `mtrr_save_fixed_ranges` Jiaqing Zhao
@ 2025-05-09 10:44 ` Borislav Petkov
0 siblings, 0 replies; 2+ messages in thread
From: Borislav Petkov @ 2025-05-09 10:44 UTC (permalink / raw)
To: Jiaqing Zhao
Cc: Thomas Gleixner, Ingo Molnar, Dave Hansen, x86, H. Peter Anvin,
Bernhard Kaindl, Andi Kleen, Li Fei, stable, linux-kernel
On Fri, May 09, 2025 at 08:56:12AM +0000, Jiaqing Zhao wrote:
> When suspending, `save_processor_state` calls `mtrr_save_fixed_ranges`
Put () after the function names and drop the ``.
> to save fixed-range MTRRs. On platforms without MTRR or fixed-range
> MTRR support, accessing MTRR MSRs triggers unchecked MSR access error.
> Make sure fixed-range MTRR is supported before access to prevent such
> error.
>
> Fixes: 3ebad5905609 ("[PATCH] x86: Save and restore the fixed-range MTRRs of the BSP when suspending")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
> ---
> arch/x86/kernel/cpu/mtrr/generic.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
> index e2c6b471d230..ca37b374d1b0 100644
> --- a/arch/x86/kernel/cpu/mtrr/generic.c
> +++ b/arch/x86/kernel/cpu/mtrr/generic.c
> @@ -593,7 +593,7 @@ static void get_fixed_ranges(mtrr_type *frs)
>
> void mtrr_save_fixed_ranges(void *info)
> {
> - if (boot_cpu_has(X86_FEATURE_MTRR))
> + if (boot_cpu_has(X86_FEATURE_MTRR) && mtrr_state.have_fixed)
Does it work too if you check only mtrr_state.have_fixed?
Without the feature check...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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