x86/pvh: Set phys_base when calling xen_prepare_pvh()

[ Upstream commit b464b46 ] 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 <[email protected]> Reviewed-by: Juergen Gross <[email protected]> Message-ID: <[email protected]> Signed-off-by: Juergen Gross <[email protected]> Stable-dep-of: e8fbc0d ("x86/pvh: Call C code via the kernel virtual mapping") Signed-off-by: Sasha Levin <[email protected]>
openbmc · Dec 9, 2024 · f662b4a · f662b4a
1 parent aa6e32c
commit f662b4a
Showing 1 changed file with 13 additions and 0 deletions.
diff --git 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