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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: |
Mon, 5 Dec 2011 11:08:42 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Sun, Dec 04, 2011 at 04:47:17PM -0700, Cam Macdonell wrote:
> On Sun, Dec 4, 2011 at 3:20 AM, Michael S. Tsirkin <address@hidden> wrote:
> > 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.
> >
> > I think the following should fix it. Compiled-only -
> > could you pls check? If yes let's apply to the stable branch.
>
> Thanks for the patch Michael.
>
> It addresses the need for msix_write_config() to be called, but the
> addition of the msix_reset() is causing a reset of the vectors after
> they've been initialized in pci_ivshmem_init(). So, interrupts still
> aren't delivered with this patch applied as it is.
>
> In particular, a reset occurs after pci_ivshmem_init runs, so the
> msix_entry_used array is reset to 0s, which causes the interrupt
> delivery to fail.
>
> If I comment out the msix_reset(), then interrupts are delivered.
> Would the reset be caused by a bug in the guest driver? or do I need
> to reconfigure the msix after reset? I'm unclear as to the proper
> behaviour after a reset.
>
> Thanks,
> Cam
>
I didn't anticipate this, virtio only configures vectors when msi-x is enabled.
For 1.0 it's safest to do the same and just re-enable after reset.
So we'll end up with something like the following - does it help?
Side note: exit(1) is not the best way to handle
errors in the init function. I think you should add error_report, then
goto err on failures to init, cleanup what you have set up
meanwhile and return an error code.
diff --git a/hw/ivshmem.c b/hw/ivshmem.c
index 242fbea..c58f4d3 100644
--- a/hw/ivshmem.c
+++ b/hw/ivshmem.c
@@ -500,11 +500,29 @@ static void ivshmem_read(void *opaque, const uint8_t *
buf, int flags)
return;
}
+/* Select the MSI-X vectors used by device.
+ * ivshmem maps events to vectors statically, so
+ * we just enable all vectors on init and after reset. */
+static void ivshmem_use_msix(IVShmemState * s)
+{
+ int i;
+
+ if (!msix_present(&s->dev)) {
+ return;
+ }
+
+ for (i = 0; i < s->vectors; i++) {
+ msix_vector_use(&s->dev, i);
+ }
+}
+
static void ivshmem_reset(DeviceState *d)
{
IVShmemState *s = DO_UPCAST(IVShmemState, dev.qdev, d);
s->intrstatus = 0;
+ msix_reset(&s->dev);
+ ivshmem_use_msix(s);
return;
}
@@ -535,12 +553,8 @@ static uint64_t ivshmem_get_size(IVShmemState * s) {
return value;
}
-static void ivshmem_setup_msi(IVShmemState * s) {
-
- int i;
-
- /* allocate the MSI-X vectors */
-
+static void ivshmem_setup_msi(IVShmemState * s)
+{
memory_region_init(&s->msix_bar, "ivshmem-msix", 4096);
if (!msix_init(&s->dev, s->vectors, &s->msix_bar, 1, 0)) {
pci_register_bar(&s->dev, 1, PCI_BASE_ADDRESS_SPACE_MEMORY,
@@ -551,13 +565,10 @@ static void ivshmem_setup_msi(IVShmemState * s) {
exit(1);
}
- /* 'activate' the vectors */
- for (i = 0; i < s->vectors; i++) {
- msix_vector_use(&s->dev, i);
- }
-
/* allocate Qemu char devices for receiving interrupts */
s->eventfd_table = g_malloc0(s->vectors * sizeof(EventfdEntry));
+
+ ivshmem_use_msix(s);
}
static void ivshmem_save(QEMUFile* f, void *opaque)
@@ -610,6 +621,13 @@ static int ivshmem_load(QEMUFile* f, void *opaque, int
version_id)
return 0;
}
+static void ivshmem_write_config(PCIDevice *pci_dev, uint32_t address,
+ uint32_t val, int len)
+{
+ pci_default_write_config(pci_dev, address, val, len);
+ msix_write_config(pci_dev, address, val, len);
+}
+
static int pci_ivshmem_init(PCIDevice *dev)
{
IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
@@ -734,6 +752,8 @@ static int pci_ivshmem_init(PCIDevice *dev)
}
+ s->dev.config_write = ivshmem_write_config;
+
return 0;
}