Commit e9576e07 authored by Yazen Ghannam's avatar Yazen Ghannam Committed by Borislav Petkov (AMD)
Browse files

x86/CPU/AMD: Ignore invalid reset reason value 



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: ab813102 ("x86/CPU/AMD: Print the reason for the last reset")
Reported-by: default avatarLibing He <libhe@redhat.com>
Signed-off-by: default avatarYazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250721181155.3536023-1-yazen.ghannam@amd.com
parent d8df1263

arch/x86/kernel/cpu/amd.c

+6 −2
Original line number Diff line number Diff line
@@ -1326,8 +1326,8 @@ 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))
@@ -1340,12 +1340,16 @@ 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]);

		}

	}