Commit 416a33c9 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Juergen Gross
Browse files

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: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: default avatarJuergen Gross <jgross@suse.com>
Message-ID: <20240802154253.482658-2-adobriyan@gmail.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
parent 661362e3

arch/x86/include/asm/cpuid.h

+6 −1
Original line number Diff line number Diff line
@@ -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;

	}