qemu-xen-trad: free all the pirqs for msi/msix when driver unload

Pirqs are not freed when driver unloads, then new pirqs are allocated when driver reloads. This could exhaust pirqs if do it in a loop.

This patch fixes the bug by freeing pirqs when ENABLE bit is cleared in msi/msix control reg.

There is also other way of fixing it such as reuse pirqs between driver reload, but this way is better.
Xen-devel: http://marc.info/?l=xen-devel&m=136800120304275&w=2

Signed-off-by Zhenzhong Duan <[email protected]>

From what I understand following the conversation, I think this is

Pirqs are not freed when driver unloads, then new pirqs are allocated when driver reloads. This could exhaust pirqs if do it in a loop.

This patch fixes the bug by freeing pirqs when ENABLE bit is cleared in msi/msix control reg.

There is also other way of fixing it such as reuse pirqs between driver reload, but this way is better.
Xen-devel: http://marc.info/?l=xen-devel&m=136800120304275&w=2

Signed-off-by Zhenzhong Duan <[email protected]>

 hw/pass-through.c |    8 +++++++-
 hw/pt-msi.c       |    5 +++--
 2 files changed, 10 insertions(+), 3 deletions(-)

hw/pass-through.c +7 -1

index 304c438..4821182 100644
@@ -3866,7 +3866,11 @@ static int pt_msgctrl_reg_write(struct pt_dev *ptdev,
         ptdev->msi->flags |= PCI_MSI_FLAGS_ENABLE;
     }
     else
-        ptdev->msi->flags &= ~PCI_MSI_FLAGS_ENABLE;
+    {
+        if (ptdev->msi->flags & PT_MSI_MAPPED) {
+            pt_msi_disable(ptdev);
+        }
+    }
 
     /* pass through MSI_ENABLE bit when no MSI-INTx translation */
     if (!ptdev->msi_trans_en) {

@@ -4013,6 +4017,8 @@ static int pt_msixctrl_reg_write(struct pt_dev *ptdev,
             pt_disable_msi_translate(ptdev);
         }
         pt_msix_update(ptdev);
+    } else if (!(*value & PCI_MSIX_ENABLE) && ptdev->msix->enabled) {
+        pt_msix_disable(ptdev);
     }
 
     ptdev->msix->enabled = !!(*value & PCI_MSIX_ENABLE);

hw/pt-msi.c +3 -2

index b03b989..3f5f94b 100644
@@ -213,7 +213,8 @@ void pt_msi_disable(struct pt_dev *dev)
 
 out:
     /* clear msi info */
-    dev->msi->flags &= ~(MSI_FLAG_UNINIT | PT_MSI_MAPPED | PCI_MSI_FLAGS_ENABLE);
+    dev->msi->flags &= ~(PT_MSI_MAPPED | PCI_MSI_FLAGS_ENABLE);
+    dev->msi->flags |= MSI_FLAG_UNINIT;
     dev->msi->pirq = -1;
     dev->msi_trans_en = 0;
 }

@@ -447,7 +448,7 @@ static void pci_msix_writel(void *opaque, target_phys_addr_t addr, uint32_t val)
     {
         const volatile uint32_t *vec_ctrl;
 
-        if ( entry->io_mem[offset] == val )
+        if ( entry->io_mem[offset] == val && entry->pirq != -1)
             return;
 
         /*

Signature · 1 line

1.7.3

Quoted 11 lines · Zhenzhong Duan

Pirqs are not freed when driver unloads, then new pirqs are allocated when driver reloads. This could exhaust pirqs if do it in a loop.

This patch fixes the bug by freeing pirqs when ENABLE bit is cleared in msi/msix control reg.

There is also other way of fixing it such as reuse pirqs between driver reload, but this way is better.
Xen-devel: http://marc.info/?l=xen-devel&m=136800120304275&w=2

Signed-off-by Zhenzhong Duan <[email protected]>

Thanks Zhenzhong.

Quoted 1 line

From what I understand following the conversation, I think this is

probably the right way to solve the problem, but given that it's only really a problem when you load and unload drivers, which is the uncommon case, I think at this point we should probably hold off on this one until 4.3.1.

Stefano, thoughts?