5.4-stable review patch. If anyone has any objections, please let me know.
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From: Jiaqing Zhao jiaqing.zhao@linux.intel.com
[ Upstream commit 824c6384e8d9275d4ec7204f3f79a4ac6bc10379 ]
When suspending, save_processor_state() calls mtrr_save_fixed_ranges() to save fixed-range MTRRs.
On platforms without fixed-range MTRRs like the ACRN hypervisor which has removed fixed-range MTRR emulation, accessing these MSRs will trigger an unchecked MSR access error. Make sure fixed-range MTRRs are supported before access to prevent such error.
Since mtrr_state.have_fixed is only set when MTRRs are present and enabled, checking the CPU feature flag in mtrr_save_fixed_ranges() is unnecessary.
Fixes: 3ebad5905609 ("[PATCH] x86: Save and restore the fixed-range MTRRs of the BSP when suspending") Signed-off-by: Jiaqing Zhao jiaqing.zhao@linux.intel.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/20250509170633.3411169-2-jiaqing.zhao@linux.intel.co... Signed-off-by: Sasha Levin sashal@kernel.org --- 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 4ea906fe1c351..d15152126877b 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -350,7 +350,7 @@ static void get_fixed_ranges(mtrr_type *frs)
void mtrr_save_fixed_ranges(void *info) { - if (boot_cpu_has(X86_FEATURE_MTRR)) + if (mtrr_state.have_fixed) get_fixed_ranges(mtrr_state.fixed_ranges); }