On December 19, 2025 1:01:31 AM UTC, Ariadne Conill ariadne@ariadne.space wrote:

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;

Sean, looka here. The other hypervisor wants other checks.

Time to whip out the X86_FEATURE_HYPERVISOR check.