From 416a33c9afcef24d8b48e414d08d4ae4472aa669 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 2 Aug 2024 18:42:52 +0300 Subject: [PATCH] x86/cpu: fix unbootable VMs by inlining memcmp() in hypervisor_cpuid_base() If this memcmp() is not inlined then PVH early boot code can call into KASAN-instrumented memcmp() which results in unbootable VMs: pvh_start_xen xen_prepare_pvh xen_cpuid_base hypervisor_cpuid_base memcmp Signed-off-by: Alexey Dobriyan Acked-by: Juergen Gross Message-ID: <20240802154253.482658-2-adobriyan@gmail.com> Signed-off-by: Juergen Gross --- arch/x86/include/asm/cpuid.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/cpuid.h b/arch/x86/include/asm/cpuid.h index 6b122a31da065..80cc6386d7b13 100644 --- a/arch/x86/include/asm/cpuid.h +++ b/arch/x86/include/asm/cpuid.h @@ -196,7 +196,12 @@ static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves) for_each_possible_hypervisor_cpuid_base(base) { cpuid(base, &eax, &signature[0], &signature[1], &signature[2]); - if (!memcmp(sig, signature, 12) && + /* + * This must not compile to "call memcmp" because it's called + * from PVH early boot code before instrumentation is set up + * and memcmp() itself may be instrumented. + */ + if (!__builtin_memcmp(sig, signature, 12) && (leaves == 0 || ((eax - base) >= leaves))) return base; } -- 2.49.0