[PATCH v7 6/8] vpci/rebar: Free Rebar resources when init_rebar() fails

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

When init_rebar() fails, current logic return fail and free Rebar-related
resources in vpci_deassign_device(). But the previous new changes will
hide Rebar capability and return success, it can't reach
vpci_deassign_device() to remove resources if hiding success, so those
resources must be removed in cleanup function of Rebar.

To do that, implement cleanup function for Rebar.

Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
---
v6->v7 changes:
* Change the pointer parameter of cleanup_rebar() to be const.
* Print error when vpci_remove_registers() fail in cleanup_rebar().

v5->v6 changes:
No.

v4->v5 changes:
* Change definition "static void cleanup_rebar" to "static int cf_check 
cleanup_rebar" since cleanup hook is changed to be int.

v3->v4 changes:
* Change function name from fini_rebar() to cleanup_rebar().
* Change the error number to be E2BIG and ENXIO in init_rebar().

v2->v3 changes:
* Use fini_rebar() to remove all register instead of in the failure path of 
init_rebar();

v1->v2 changes:
* Called vpci_remove_registers() to remove all possible registered registers 
instead of using a array to record all registered register.

Best regards,
Jiqian Chen.
---
 xen/drivers/vpci/rebar.c | 41 +++++++++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/xen/drivers/vpci/rebar.c b/xen/drivers/vpci/rebar.c
index 3c18792d9bcd..39ab9c2eb7d9 100644
--- a/xen/drivers/vpci/rebar.c
+++ b/xen/drivers/vpci/rebar.c
@@ -49,6 +49,32 @@ static void cf_check rebar_ctrl_write(const struct pci_dev 
*pdev,
     bar->guest_addr = bar->addr;
 }
 
+static int cf_check cleanup_rebar(const struct pci_dev *pdev)
+{
+    int rc;
+    uint32_t ctrl;
+    unsigned int nbars;
+    unsigned int rebar_offset = pci_find_ext_capability(pdev->sbdf,
+                                                        PCI_EXT_CAP_ID_REBAR);
+
+    if ( !rebar_offset || !is_hardware_domain(pdev->domain) )
+    {
+        ASSERT_UNREACHABLE();
+        return 0;
+    }
+
+    ctrl = pci_conf_read32(pdev->sbdf, rebar_offset + PCI_REBAR_CTRL(0));
+    nbars = MASK_EXTR(ctrl, PCI_REBAR_CTRL_NBAR_MASK);
+
+    rc = vpci_remove_registers(pdev->vpci, rebar_offset + PCI_REBAR_CAP(0),
+                               PCI_REBAR_CTRL(nbars - 1));
+    if ( rc )
+        printk(XENLOG_ERR "%pd %pp: fail to remove Rebar handlers rc=%d\n",
+               pdev->domain, &pdev->sbdf, rc);
+
+    return rc;
+}
+
 static int cf_check init_rebar(struct pci_dev *pdev)
 {
     uint32_t ctrl;
@@ -80,7 +106,7 @@ static int cf_check init_rebar(struct pci_dev *pdev)
         {
             printk(XENLOG_ERR "%pd %pp: too big BAR number %u in REBAR_CTRL\n",
                    pdev->domain, &pdev->sbdf, index);
-            continue;
+            return -E2BIG;
         }
 
         bar = &pdev->vpci->header.bars[index];
@@ -88,7 +114,7 @@ static int cf_check init_rebar(struct pci_dev *pdev)
         {
             printk(XENLOG_ERR "%pd %pp: BAR%u is not in memory space\n",
                    pdev->domain, &pdev->sbdf, index);
-            continue;
+            return -ENXIO;
         }
 
         rc = vpci_add_register(pdev->vpci, vpci_hw_read32, rebar_ctrl_write,
@@ -97,14 +123,7 @@ static int cf_check init_rebar(struct pci_dev *pdev)
         {
             printk(XENLOG_ERR "%pd %pp: BAR%u fail to add reg of REBAR_CTRL 
rc=%d\n",
                    pdev->domain, &pdev->sbdf, index, rc);
-            /*
-             * Ideally we would hide the ReBar capability on error, but code
-             * for doing so still needs to be written. Use continue instead
-             * to keep any already setup register hooks, as returning an
-             * error will cause the hardware domain to get unmediated access
-             * to all device registers.
-             */
-            continue;
+            return rc;
         }
 
         bar->resizable_sizes =
@@ -118,7 +137,7 @@ static int cf_check init_rebar(struct pci_dev *pdev)
 
     return 0;
 }
-REGISTER_VPCI_EXTCAP(REBAR, init_rebar, NULL);
+REGISTER_VPCI_EXTCAP(REBAR, init_rebar, cleanup_rebar);
 
 /*
  * Local variables:
-- 
2.34.1