[Qemu-devel] [PATCH v2 0/2] vfio: Warn on failure to read device rom

[Qemu-devel] [PATCH v2 0/2] vfio: Warn on failure to read device rom

[Bandan Das]

Minor changes to print a message on the monitor
console in case of a rom read failure. Please see individual
patches for more details.

Bandan Das (2):
  vfio: warn if host device rom can't be read
  vfio: Do not reattempt a failed rom read

 hw/misc/vfio.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

-- 
1.8.3.1

[Qemu-devel] [PATCH v2 1/2] vfio: warn if host device rom can't be read

[Bandan Das]

If the device rom can't be read, report an error to the
user. This alerts the user that the device has a bad
state that is causing rom read failure or option rom
loading has been disabled from the device boot menu
(among other reasons).

Signed-off-by: Bandan Das <bsd@redhat.com>
---
v2: Removed the macros to print only once. We want to print
the warning message for each assigned device for which rom 
read fails

 hw/misc/vfio.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index 9aecaa8..d2e68e2 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -1125,6 +1125,13 @@ static void vfio_pci_load_rom(VFIODevice *vdev)
     vdev->rom_offset = reg_info.offset;
 
     if (!vdev->rom_size) {
+        error_report("vfio-pci: Cannot read device rom at "
+                    "%04x:%02x:%02x.%x\n",
+                    vdev->host.domain, vdev->host.bus, vdev->host.slot,
+                    vdev->host.function);
+        error_printf("Device option ROM contents are probably invalid "
+                    "(check dmesg).\nSkip option ROM probe with rombar=0, "
+                    "or load from file with romfile=\n");
         return;
     }
 
-- 
1.8.3.1

[Qemu-devel] [PATCH v2 2/2] vfio: Do not reattempt a failed rom read

[Bandan Das]

During lazy rom loading, if rom read fails, and the
guest attempts a read again, vfio will again attempt it.
Add a boolean to prevent this. There could be a case where
a failed rom read might succeed the next time because of
a device reset or such, but it's best to exclude unpredictable
behavior

Signed-off-by: Bandan Das <bsd@redhat.com>
---
v2: Check for vdev->rom first followed by the rom_read_failed flag

 hw/misc/vfio.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index d2e68e2..5ed9cbe 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -191,6 +191,7 @@ typedef struct VFIODevice {
     bool has_flr;
     bool has_pm_reset;
     bool needs_reset;
+    bool rom_read_failed;
 } VFIODevice;
 
 typedef struct VFIOGroup {
@@ -1125,6 +1126,7 @@ static void vfio_pci_load_rom(VFIODevice *vdev)
     vdev->rom_offset = reg_info.offset;
 
     if (!vdev->rom_size) {
+        vdev->rom_read_failed = true;
         error_report("vfio-pci: Cannot read device rom at "
                     "%04x:%02x:%02x.%x\n",
                     vdev->host.domain, vdev->host.bus, vdev->host.slot,
@@ -1163,6 +1165,9 @@ static uint64_t vfio_rom_read(void *opaque, hwaddr addr, unsigned size)
     /* Load the ROM lazily when the guest tries to read it */
     if (unlikely(!vdev->rom)) {
         vfio_pci_load_rom(vdev);
+        if (unlikely(!vdev->rom && !vdev->rom_read_failed)) {
+            vfio_pci_load_rom(vdev);
+        }
     }
 
     memcpy(&val, vdev->rom + addr,
@@ -1230,6 +1235,7 @@ static void vfio_pci_size_rom(VFIODevice *vdev)
                      PCI_BASE_ADDRESS_SPACE_MEMORY, &vdev->pdev.rom);
 
     vdev->pdev.has_rom = true;
+    vdev->rom_read_failed = false;
 }
 
 static void vfio_vga_write(void *opaque, hwaddr addr,
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH v2 0/2] vfio: Warn on failure to read device rom

[Alex Williamson]

On Wed, 2014-01-15 at 15:38 +0530, Bandan Das wrote:
> Minor changes to print a message on the monitor
> console in case of a rom read failure. Please see individual
> patches for more details.
> 
> Bandan Das (2):
>   vfio: warn if host device rom can't be read
>   vfio: Do not reattempt a failed rom read
> 
>  hw/misc/vfio.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 

These look fine to me, I'll include them in my next pull request.
Thanks!

Alex