[PATCH 4/4] vpci/header: empty the BAR range sets when modify_bars() fails

[Stefano Stabellini <stefano.stabellini@xxxxxxx>]

On error modify_bars() returned with the ranges already collected still
in the per-BAR sets. The next request on the device then maps or unmaps
them along with its own. Purge every set when collecting the ranges
fails.

Fixes: 622bdd962822 ("vpci/header: handle p2m range sets per BAR")
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
Cc: "Roger Pau Monné" <roger@xxxxxxxxxxxxxx>
Cc: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
---
 xen/drivers/vpci/header.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
index 7e5f4b8a00..0bdc4d6a46 100644
--- a/xen/drivers/vpci/header.c
+++ b/xen/drivers/vpci/header.c
@@ -366,7 +366,8 @@ static int modify_bars(const struct pci_dev *pdev, uint16_t 
cmd, bool rom_only)
             gprintk(XENLOG_G_WARNING,
                     "%pp: can't map BAR%u - offset mismatch: %#lx vs %#lx\n",
                     &pdev->sbdf, i, bar->guest_addr, bar->addr);
-            return -EINVAL;
+            rc = -EINVAL;
+            goto fail;
         }
 
         rc = rangeset_add_range(bar->mem, start_guest, end_guest);
@@ -374,7 +375,7 @@ static int modify_bars(const struct pci_dev *pdev, uint16_t 
cmd, bool rom_only)
         {
             printk(XENLOG_G_WARNING "Failed to add [%lx, %lx]: %d\n",
                    start_guest, end_guest, rc);
-            return rc;
+            goto fail;
         }
 
         /* Check for overlap with the already setup BAR ranges. */
@@ -391,7 +392,7 @@ static int modify_bars(const struct pci_dev *pdev, uint16_t 
cmd, bool rom_only)
                 gprintk(XENLOG_WARNING,
                        "%pp: failed to remove overlapping range [%lx, %lx]: 
%d\n",
                         &pdev->sbdf, start_guest, end_guest, rc);
-                return rc;
+                goto fail;
             }
         }
 
@@ -401,7 +402,7 @@ static int modify_bars(const struct pci_dev *pdev, uint16_t 
cmd, bool rom_only)
             gprintk(XENLOG_WARNING,
                     "%pp: failed to sanitize BAR#%u memory: %d\n",
                     &pdev->sbdf, i, rc);
-            return rc;
+            goto fail;
         }
     }
 
@@ -425,7 +426,7 @@ static int modify_bars(const struct pci_dev *pdev, uint16_t 
cmd, bool rom_only)
                 gprintk(XENLOG_WARNING,
                        "%pp: failed to remove MSIX table [%lx, %lx]: %d\n",
                         &pdev->sbdf, start, end, rc);
-                return rc;
+                goto fail;
             }
         }
     }
@@ -487,7 +488,7 @@ static int modify_bars(const struct pci_dev *pdev, uint16_t 
cmd, bool rom_only)
                         gprintk(XENLOG_WARNING,
                                 "%pp: failed to remove [%lx, %lx]: %d\n",
                                 &pdev->sbdf, start, end, rc);
-                        return rc;
+                        goto fail;
                     }
                 }
             }
@@ -516,6 +517,18 @@ static int modify_bars(const struct pci_dev *pdev, 
uint16_t cmd, bool rom_only)
     defer_map(pdev, cmd, rom_only);
 
     return 0;
+
+ fail:
+    /*
+     * Leave no range collected for the request that failed: the next request
+     * expects every BAR's set to start empty, and a range left behind would
+     * be mapped or unmapped with it.
+     */
+    for ( i = 0; i < ARRAY_SIZE(header->bars); i++ )
+        if ( header->bars[i].mem )
+            rangeset_purge(header->bars[i].mem);
+
+    return rc;
 }
 
 static void cf_check cmd_write(
-- 
2.43.0