[Xen-devel] [PATCH] x86/MSI: handle both MSI-X and MSI in cfg space write intercept

["Jan Beulich" <JBeulich@xxxxxxxx>]

In commit aa7c1fdf9d ("x86/MSI: properly track guest masking requests")
I neglected to consider devices allowing for both MSI and MSI-X to be
used (not at the same time of course): The MSI-X part of the intercept
logic needs to fall through to the MSI one when the access is outside
the MSI-X capability bounds.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -1292,17 +1292,17 @@ int pci_msi_conf_write_intercept(struct
                                           PCI_CAP_ID_MSIX);
         ASSERT(pos);
 
-        if ( reg < pos || reg >= msix_pba_offset_reg(pos) + 4 )
-            return 0;
+        if ( reg >= pos && reg < msix_pba_offset_reg(pos) + 4 )
+        {
+            if ( reg != msix_control_reg(pos) || size != 2 )
+                return -EACCES;
 
-        if ( reg != msix_control_reg(pos) || size != 2 )
-            return -EACCES;
+            pdev->msix->guest_maskall = !!(*data & PCI_MSIX_FLAGS_MASKALL);
+            if ( pdev->msix->host_maskall )
+                *data |= PCI_MSIX_FLAGS_MASKALL;
 
-        pdev->msix->guest_maskall = !!(*data & PCI_MSIX_FLAGS_MASKALL);
-        if ( pdev->msix->host_maskall )
-            *data |= PCI_MSIX_FLAGS_MASKALL;
-
-        return 1;
+            return 1;
+        }
     }
 
     entry = find_msi_entry(pdev, -1, PCI_CAP_ID_MSI);

Attachment: x86-MSI-intercept-both.patch
Description: Text document

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