xen/pt: correctly handle PM status bit

xen_pt_pmcsr_reg_write() needs an adjustment to deal with the RW1C
nature of the not passed through bit 15 (PCI_PM_CTRL_PME_STATUS).

This is a preparatory patch for XSA-131.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
index 516236a3f0739556070c59ec3c7f4c96cc3b8ba0..027ac324b36c16b4944d29588be9f1b4298fbc92 100644 (file)
--- a/hw/xen/xen_pt_config_init.c
+++ b/hw/xen/xen_pt_config_init.c
@@ -948,7 +948,8 @@ static int xen_pt_pmcsr_reg_write(XenPCIPassthroughState *s,
 
     /* create value for writing to I/O device register */
     throughable_mask = ~reg->emu_mask & valid_mask;
-    *val = XEN_PT_MERGE_VALUE(*val, dev_value, throughable_mask);
+    *val = XEN_PT_MERGE_VALUE(*val, dev_value & ~PCI_PM_CTRL_PME_STATUS,
+                              throughable_mask);
 
     return 0;
 }