linux-kernel - [PATCH 1/3] xen, pvh: fix unbootable VMs (PVH + KASAN)

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Message-ID: <a9f505a6-fd31-4cfa-a193-d21638bb14f1@p183>
Date: Thu, 1 Aug 2024 22:16:56 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: Juergen Gross <jgross@...e.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] xen, pvh: fix unbootable VMs (PVH + KASAN)

Uninstrument arch/x86/platform/pvh/enlighten.c: KASAN is not setup
_this_ early in the boot process.

Steps to reproduce:

	make allnoconfig
	make sure CONFIG_AMD_MEM_ENCRYPT is disabled
		AMD_MEM_ENCRYPT independently uninstruments lib/string.o
		so PVH boot code calls into uninstrumented memset() and
		memcmp() which can make the bug disappear depending on
		the compiler.
	enable CONFIG_PVH
	enable CONFIG_KASAN
	enable serial console
		this is fun exercise if you never done it from nothing :^)

	make

	qemu-system-x86_64	\
		-enable-kvm	\
		-cpu host	\
		-smp cpus=1	\
		-m 4096		\
		-serial stdio	\
		-kernel vmlinux \
		-append 'console=ttyS0 ignore_loglevel'

Messages on serial console will easily tell OK kernel from unbootable
kernel. In bad case qemu hangs in an infinite loop stroboscoping
"SeaBIOS" message.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 arch/x86/platform/pvh/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/platform/pvh/Makefile b/arch/x86/platform/pvh/Makefile
index 5dec5067c9fb..c43fb7964dc4 100644
--- a/arch/x86/platform/pvh/Makefile
+++ b/arch/x86/platform/pvh/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 OBJECT_FILES_NON_STANDARD_head.o := y
+KASAN_SANITIZE := n
 
 obj-$(CONFIG_PVH) += enlighten.o
 obj-$(CONFIG_PVH) += head.o