From 7d06af2fa25b41ecd9f470c3d2a8ff3757bae637 Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Mon, 21 Jul 2025 18:11:54 +0000 Subject: [PATCH] x86/CPU/AMD: Ignore invalid reset reason value commit e9576e078220c50ace9e9087355423de23e25fa5 upstream. The reset reason value may be "all bits set", e.g. 0xFFFFFFFF. This is a commonly used error response from hardware. This may occur due to a real hardware issue or when running in a VM. The user will see all reset reasons reported in this case. Check for an error response value and return early to avoid decoding invalid data. Also, adjust the data variable type to match the hardware register size. Fixes: ab8131028710 ("x86/CPU/AMD: Print the reason for the last reset") Reported-by: Libing He Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello Cc: stable@vger.kernel.org Link: https://lore.kernel.org/20250721181155.3536023-1-yazen.ghannam@amd.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/amd.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 329ee185d8cca..9cc1738f59cf5 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1324,8 +1324,8 @@ static const char * const s5_reset_reason_txt[] = { static __init int print_s5_reset_status_mmio(void) { - unsigned long value; void __iomem *addr; + u32 value; int i; if (!cpu_feature_enabled(X86_FEATURE_ZEN)) @@ -1338,12 +1338,16 @@ static __init int print_s5_reset_status_mmio(void) value = ioread32(addr); iounmap(addr); + /* Value with "all bits set" is an error response and should be ignored. */ + if (value == U32_MAX) + return 0; + for (i = 0; i < ARRAY_SIZE(s5_reset_reason_txt); i++) { if (!(value & BIT(i))) continue; if (s5_reset_reason_txt[i]) { - pr_info("x86/amd: Previous system reset reason [0x%08lx]: %s\n", + pr_info("x86/amd: Previous system reset reason [0x%08x]: %s\n", value, s5_reset_reason_txt[i]); } } -- 2.47.3