[PATCH 6.18 049/752] x86/xen/pvh: Enable PAE mode for 32-bit guest only when CONFIG_X86_PAE is set

Sasha Levin
2026-02-28T17:48:50Z

From: Hou Wenlong <houwenlong.hwl@antgroup.com>

[ Upstream commit db9aded979b491a24871e1621cd4e8822dbca859 ]

The PVH entry is available for 32-bit KVM guests, and 32-bit KVM guests
do not depend on CONFIG_X86_PAE. However, mk_early_pgtbl_32() builds
different pagetables depending on whether CONFIG_X86_PAE is set.
Therefore, enabling PAE mode for 32-bit KVM guests without
CONFIG_X86_PAE being set would result in a boot failure during CR3
loading.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <d09ce9a134eb9cbc16928a5b316969f8ba606b81.1768017442.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/platform/pvh/head.S | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index 344030c1a81d4..53ee2d53fcf8e 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -91,10 +91,12 @@ SYM_CODE_START(pvh_start_xen)

leal rva(early_stack_end)(%ebp), %esp

+#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
/* Enable PAE mode. */
mov %cr4, %eax
orl $X86_CR4_PAE, %eax
mov %eax, %cr4
+#endif

#ifdef CONFIG_X86_64
/* Enable Long mode. */
--
2.51.0