[PATCH v3 10/11] vpci/msi: Free MSI resources when init_msi() fails

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

When init_msi() fails, the previous new changes will hide MSI
capability, it can't rely on vpci_deassign_device() to remove
all MSI related resources anymore, those resources must be
cleaned up in failure path of init_msi.

To do that, add a new function to free MSI resources.

Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
---
v2->v3 changes:
* Remove all fail path, and use fini_msi() hook instead.
* Change the method to calculating the size of msi registers.

v1->v2 changes:
* Added a new function fini_msi to free all MSI resources instead of using an 
array to record registered registers.

Best regards,
Jiqian Chen.
---
 xen/drivers/vpci/msi.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/xen/drivers/vpci/msi.c b/xen/drivers/vpci/msi.c
index ea7dc0c060ea..18b06b789827 100644
--- a/xen/drivers/vpci/msi.c
+++ b/xen/drivers/vpci/msi.c
@@ -193,6 +193,32 @@ static void cf_check mask_write(
     msi->mask = val;
 }
 
+static void fini_msi(struct pci_dev *pdev)
+{
+    unsigned int end, size;
+    struct vpci *vpci = pdev->vpci;
+    const unsigned int msi_pos = pdev->msi_pos;
+
+    if ( !msi_pos || !vpci->msi )
+        return;
+
+    if ( vpci->msi->masking )
+        end = msi_pending_bits_reg(msi_pos, vpci->msi->address64);
+    else
+        end = msi_mask_bits_reg(msi_pos, vpci->msi->address64) - 2;
+
+    size = end - msi_control_reg(msi_pos);
+
+    /*
+     * Remove all possible registered registers except capability ID
+     * register if guest and next capability pointer register, which
+     * will be removed in mask function.
+     */
+    vpci_remove_registers(vpci, msi_control_reg(msi_pos), size);
+    xfree(vpci->msi);
+    vpci->msi = NULL;
+}
+
 static int cf_check init_msi(struct pci_dev *pdev)
 {
     unsigned int pos = pdev->msi_pos;
@@ -270,7 +296,7 @@ static int cf_check init_msi(struct pci_dev *pdev)
 
     return 0;
 }
-REGISTER_VPCI_LEGACY_CAP(PCI_CAP_ID_MSI, init_msi, NULL);
+REGISTER_VPCI_LEGACY_CAP(PCI_CAP_ID_MSI, init_msi, fini_msi);
 
 void vpci_dump_msi(void)
 {
-- 
2.34.1