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Re: [Qemu-devel] [PATCH for v1.0 1/3] msix: track function masked in pci
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH for v1.0 1/3] msix: track function masked in pci device state |
Date: |
Sun, 4 Dec 2011 12:08:42 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Dec 02, 2011 at 04:34:21PM -0700, Cam Macdonell wrote:
> Based on a git bisect, this patch breaks msi-x interrupt delivery in
> the ivshmem device.
>
> On Mon, Nov 21, 2011 at 9:57 AM, Michael S. Tsirkin <address@hidden> wrote:
> > Only go over the table when function is masked.
> > This is not really important for qemu.git but helps
> > fix a bug in qemu-kvm.git.
> >
> > Signed-off-by: Michael S. Tsirkin <address@hidden>
> > ---
> > hw/msix.c | 21 ++++++++++++++-------
> > hw/pci.h | 2 ++
> > 2 files changed, 16 insertions(+), 7 deletions(-)
> >
> > diff --git a/hw/msix.c b/hw/msix.c
> > index b15bafc..63b41b9 100644
> > --- a/hw/msix.c
> > +++ b/hw/msix.c
> > @@ -79,6 +79,7 @@ static int msix_add_config(struct PCIDevice *pdev,
> > unsigned short nentries,
> > /* Make flags bit writable. */
> > pdev->wmask[config_offset + MSIX_CONTROL_OFFSET] |= MSIX_ENABLE_MASK |
> > MSIX_MASKALL_MASK;
> > + pdev->msix_function_masked = true;
> > return 0;
>
> iiuc, this masks the msix by default.
Yes, because msi-x is disabled by default, that's
in the pci spec.
> > }
> >
> > @@ -117,16 +118,11 @@ static void msix_clr_pending(PCIDevice *dev, int
> > vector)
> > *msix_pending_byte(dev, vector) &= ~msix_pending_mask(vector);
> > }
> >
> > -static int msix_function_masked(PCIDevice *dev)
> > -{
> > - return dev->config[dev->msix_cap + MSIX_CONTROL_OFFSET] &
> > MSIX_MASKALL_MASK;
> > -}
> > -
> > static int msix_is_masked(PCIDevice *dev, int vector)
> > {
> > unsigned offset =
> > vector * PCI_MSIX_ENTRY_SIZE + PCI_MSIX_ENTRY_VECTOR_CTRL;
> > - return msix_function_masked(dev) ||
> > + return dev->msix_function_masked ||
> > dev->msix_table_page[offset] & PCI_MSIX_ENTRY_CTRL_MASKBIT;
> > }
> >
> > @@ -138,24 +134,34 @@ static void msix_handle_mask_update(PCIDevice *dev,
> > int vector)
> > }
> > }
> >
> > +static void msix_update_function_masked(PCIDevice *dev)
> > +{
> > + dev->msix_function_masked = !msix_enabled(dev) ||
> > + (dev->config[dev->msix_cap + MSIX_CONTROL_OFFSET] &
> > MSIX_MASKALL_MASK);
> > +}
> > +
> > /* Handle MSI-X capability config write. */
> > void msix_write_config(PCIDevice *dev, uint32_t addr,
> > uint32_t val, int len)
> > {
> > unsigned enable_pos = dev->msix_cap + MSIX_CONTROL_OFFSET;
> > int vector;
> > + bool was_masked;
> >
> > if (!range_covers_byte(addr, len, enable_pos)) {
> > return;
> > }
> >
> > + was_masked = dev->msix_function_masked;
> > + msix_update_function_masked(dev);
> > +
> > if (!msix_enabled(dev)) {
> > return;
> > }
> >
> > pci_device_deassert_intx(dev);
> >
> > - if (msix_function_masked(dev)) {
> > + if (dev->msix_function_masked == was_masked) {
> > return;
> > }
>
> So I believe my bug is due to the fact the new logic included in this
> patch requires msix_write_config() to be called to unmask the vectors.
Not exactly, to enable msi-x really.
> Virtio-pci calls msix_write_config(), but ivshmem does not (nor does
> PCIe so I'm not sure if it's also affected).
At this point PCIe is a stub.
> I haven't been able to fix the bug yet, but I wanted to make sure I
> was looking in the correct place. Any help of further explanation of
> this patch would be greatly appreciated.
>
> Sincerely,
> Cam
So I think you just need to call msix_write_config,
otherwise msix is not getting enabled.
BTW looking at the ivshmem code, this bit looks wrong:
pci_conf[PCI_COMMAND] = PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
I think the spec says IO/MEMORY must be disabled at init time since BARs
are not yet set to anything reasonable.
> >
> > @@ -300,6 +306,7 @@ void msix_load(PCIDevice *dev, QEMUFile *f)
> > msix_free_irq_entries(dev);
> > qemu_get_buffer(f, dev->msix_table_page, n * PCI_MSIX_ENTRY_SIZE);
> > qemu_get_buffer(f, dev->msix_table_page + MSIX_PAGE_PENDING, (n + 7) /
> > 8);
> > + msix_update_function_masked(dev);
> > }
> >
> > /* Does device support MSI-X? */
> > diff --git a/hw/pci.h b/hw/pci.h
> > index 4b2e785..625e717 100644
> > --- a/hw/pci.h
> > +++ b/hw/pci.h
> > @@ -178,6 +178,8 @@ struct PCIDevice {
> > unsigned *msix_entry_used;
> > /* Region including the MSI-X table */
> > uint32_t msix_bar_size;
> > + /* MSIX function mask set or MSIX disabled */
> > + bool msix_function_masked;
> > /* Version id needed for VMState */
> > int32_t version_id;
> >
> > --
> > 1.7.5.53.gc233e
> >
> >