[PATCH 3/3] xen, pvh: fix unbootable VMs by inlining memset in xen_prepare_pvh

[Alexey Dobriyan <adobriyan@xxxxxxxxx>]

If this memset() is not inlined than PVH early boot code can call
into KASAN-instrumented memset() which results in unbootable VMs.

Ubuntu's 22.04.4 LTS gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04)
doesn't inline this memset but inlines __builtin_memset.

Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
---

 arch/x86/platform/pvh/enlighten.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/pvh/enlighten.c 
b/arch/x86/platform/pvh/enlighten.c
index 8c2d4b8de25d..c2f6e202217c 100644
--- a/arch/x86/platform/pvh/enlighten.c
+++ b/arch/x86/platform/pvh/enlighten.c
@@ -133,7 +133,8 @@ void __init xen_prepare_pvh(void)
                BUG();
        }
 
-       memset(&pvh_bootparams, 0, sizeof(pvh_bootparams));
+       /* This can compile to "call memset" and memset() can be instrumented. 
*/
+       __builtin_memset(&pvh_bootparams, 0, sizeof(pvh_bootparams));
 
        hypervisor_specific_init(xen_guest);