linux-kernel - [PATCH 3/3] xen, pvh: fix unbootable VMs by inlining memset() in xen_prepare

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Message-ID: <20240802154253.482658-3-adobriyan@gmail.com>
Date: Fri,  2 Aug 2024 18:42:53 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: jgross@...e.com,
	boris.ostrovsky@...cle.com,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com
Cc: adobriyan@...il.com,
	linux-kernel@...r.kernel.org,
	x86@...nel.org,
	hpa@...or.com
Subject: [PATCH 3/3] xen, pvh: fix unbootable VMs by inlining memset() in xen_prepare_pvh()

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

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
 arch/x86/platform/pvh/enlighten.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/pvh/enlighten.c b/arch/x86/platform/pvh/enlighten.c
index 944e0290f2c0..2263885d16ba 100644
--- a/arch/x86/platform/pvh/enlighten.c
+++ b/arch/x86/platform/pvh/enlighten.c
@@ -130,7 +130,11 @@ void __init xen_prepare_pvh(void)
 		BUG();
 	}
 
-	memset(&pvh_bootparams, 0, sizeof(pvh_bootparams));
+	/*
+	 * This must not compile to "call memset" because memset() may be
+	 * instrumented.
+	 */
+	__builtin_memset(&pvh_bootparams, 0, sizeof(pvh_bootparams));
 
 	hypervisor_specific_init(xen_guest);
 
-- 
2.45.0