Re: [Qemu-devel] [PATCH 2/2 v2] pcie_aer: clear cmask for Advanced Error Interrupt Message Number

[Jason Baron <jbaron@redhat.com>]

On Fri, Aug 31, 2012 at 11:43:31AM -0400, Jason Baron wrote:
> On Fri, Aug 31, 2012 at 06:35:13PM +0300, Michael S. Tsirkin wrote:
> > On Fri, Aug 31, 2012 at 10:45:52AM -0400, Jason Baron wrote:
> > > On Fri, Aug 31, 2012 at 11:42:27AM +0300, Michael S. Tsirkin wrote:
> > > > Some minor nits below. If you dont get to it I will tweak this patch
> > > > when I apply it early next week.
> > > > 
> > > > On Thu, Aug 30, 2012 at 01:51:15PM -0400, Jason Baron wrote:
> > > > > The Advanced Error Interrupt Message Number (bits 31:27 of the Root
> > > > > Error Status Register) is updated when the number of msi messages assigned to a
> > > > > device changes. Migration of windows 7 on q35 chipset failed because the check
> > > > > in get_pci_config_device() fails due to wmask being set on these bits.
> > > > 
> > > > I think you actually mean 'not being set on these bits'?
> > > > 
> > > 
> > > No, the check is:
> > > 
> > > static int get_pci_config_device(QEMUFile *f, void *pv, size_t size)
> > > {
> > >     PCIDevice *s = container_of(pv, PCIDevice, config);
> > >     uint8_t *config;
> > >     int i;
> > > 
> > >     assert(size == pci_config_size(s));
> > >     config = g_malloc(size);
> > > 
> > >     qemu_get_buffer(f, config, size);
> > >     for (i = 0; i < size; ++i) {
> > >         if ((config[i] ^ s->config[i]) &
> > >             s->cmask[i] & ~s->wmask[i] & ~s->w1cmask[i]) {
> > >             g_free(config);
> > >             return -EINVAL;
> > >         }
> > >     }
> > > .....
> > > 
> > > So because cmask is set and these bits differ in config space (due to
> > > them being updated before migration), the migration aborts.
> > 
> > Ah so you mean 'cmask being set' - not wmask as you wrote.
> > 
> 
> Sorry - my mistake, yes I meant 'cmask'. I will fix the changelog in the
> re-post.
> 

Ok, here's a v2:

---

pcie_aer: clear cmask for Advanced Error Interrupt Message Number

The Advanced Error Interrupt Message Number (bits 31:27 of the Root
Error Status Register) is updated when the number of msi messages assigned to a
device changes. Migration of windows 7 on q35 chipset failed because the check
in get_pci_config_device() fails due to cmask being set on these bits. Its valid
to update these bits and we must restore this state across migration.

Signed-off-by: Jason Baron <jbaron@redhat.com>
---

v2:
- Based on Michael Tsirkin's feedback:
    -updated changelog 'wmask' -> 'cmask'
    -Cleaned up comments
    -Make cmask set more readable

 hw/pcie_aer.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/hw/pcie_aer.c b/hw/pcie_aer.c
index 3b6981c..b04c164 100644
--- a/hw/pcie_aer.c
+++ b/hw/pcie_aer.c
@@ -738,6 +738,11 @@ void pcie_aer_root_init(PCIDevice *dev)
                  PCI_ERR_ROOT_CMD_EN_MASK);
     pci_set_long(dev->w1cmask + pos + PCI_ERR_ROOT_STATUS,
                  PCI_ERR_ROOT_STATUS_REPORT_MASK);
+    /* PCI_ERR_ROOT_IRQ is RO but devices change it using a
+     * device-specific method.
+     */
+    pci_set_long(dev->cmask + pos + PCI_ERR_ROOT_STATUS,
+                 ~PCI_ERR_ROOT_IRQ);
 }
 
 void pcie_aer_root_reset(PCIDevice *dev)
-- 
1.7.1