[PATCH] x86/CPU/AMD: avoid printing reset reasons on Xen domU

Ariadne Conill
2025-12-19T01:01:44Z

Xen domU cannot access the given MMIO address for security reasons,
resulting in a failed hypercall in ioremap() due to permissions.

Fixes: ab8131028710 ("x86/CPU/AMD: Print the reason for the last reset")
Signed-off-by: Ariadne Conill <ariadne@ariadne.space>
Cc: xen-devel@lists.xenproject.org
Cc: stable@vger.kernel.org
---
arch/x86/kernel/cpu/amd.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index a6f88ca1a6b4..99308fba4d7d 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -29,6 +29,8 @@
# include <asm/mmconfig.h>
#endif

+#include <xen/xen.h>
+
#include "cpu.h"

u16 invlpgb_count_max __ro_after_init = 1;
@@ -1333,6 +1335,10 @@ static __init int print_s5_reset_status_mmio(void)
if (!cpu_feature_enabled(X86_FEATURE_ZEN))
return 0;

+ /* Xen PV domU cannot access hardware directly, so bail for domU case */
+ if (cpu_feature_enabled(X86_FEATURE_XENPV) && !xen_initial_domain())
+ return 0;
+
addr = ioremap(FCH_PM_BASE + FCH_PM_S5_RESET_STATUS, sizeof(value));
if (!addr)
return 0;
--
2.51.0