From: Jiaqing Zhao Date: Fri, 9 May 2025 17:06:33 +0000 (+0000) Subject: x86/mtrr: Check if fixed-range MTRRs exist in mtrr_save_fixed_ranges() X-Git-Tag: v6.16-rc1~180^2 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=824c6384e8d9275d4ec7204f3f79a4ac6bc10379;p=linux-block.git x86/mtrr: Check if fixed-range MTRRs exist in mtrr_save_fixed_ranges() 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 Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/20250509170633.3411169-2-jiaqing.zhao@linux.intel.com --- diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index e2c6b471d230..8c18327eb10b 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 (mtrr_state.have_fixed) get_fixed_ranges(mtrr_state.fixed_ranges); }