6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jason Andryuk <jason.andryuk@xxxxxxx>
[ 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>
---
arch/x86/platform/pvh/head.S | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index c4365a05ab83b..c994ea58bdf7a 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -100,7 +100,20 @@ 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
--
2.43.0
