This is a note to let you know that I've just added the patch titled
x86/pvh: Set phys_base when calling xen_prepare_pvh()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-pvh-set-phys_base-when-calling-xen_prepare_pvh.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f250731baac8e75ace3cec56e22c979aadb1f1ae
Author: Jason Andryuk <jason.andryuk@xxxxxxx>
Date: Fri Aug 23 15:36:28 2024 -0400
x86/pvh: Set phys_base when calling xen_prepare_pvh()
[ Upstream commit b464b461d27d564125db760938643374864c1b1f ]
phys_base needs to be set for __pa() to work in xen_pvh_init() when
finding the hypercall page. Set it before calling into
xen_prepare_pvh(), which calls xen_pvh_init(). Clear it afterward to
avoid __startup_64() adding to it and creating an incorrect value.
Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Message-ID: <20240823193630.2583107-4-jason.andryuk@xxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Stable-dep-of: e8fbc0d9cab6 ("x86/pvh: Call C code via the kernel virtual mapping")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index b0490701da2ab..cfabc3340362b 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -99,7 +99,20 @@ SYM_CODE_START_LOCAL(pvh_start_xen)
xor %edx, %edx
wrmsr
+ /*
+ * Calculate load offset and store in phys_base. __pa() needs
+ * phys_base set to calculate the hypercall page in xen_pvh_init().
+ */
+ movq %rbp, %rbx
+ subq $_pa(pvh_start_xen), %rbx
+ movq %rbx, phys_base(%rip)
call xen_prepare_pvh
+ /*
+ * Clear phys_base. __startup_64 will *add* to its value,
+ * so reset to 0.
+ */
+ xor %rbx, %rbx
+ movq %rbx, phys_base(%rip)
/* startup_64 expects boot_params in %rsi. */
mov $_pa(pvh_bootparams), %rsi
