[Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Marc-André Lureau]

With vga=775 on the Linux command line a first boot of the VM running
Linux works fine. After a warm reboot it crashes during Linux boot.

Before that, valgrind points out bad memory write to console
surface. The VGA code is not aware that virtio-gpu got a message
surface scanout when the display is disabled. Let's reset VGA graphic
mode when it is the case, so that a new display surface is created
when doing further VGA operations.

https://bugs.launchpad.net/qemu/+bug/1784900/

Reported-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 include/hw/virtio/virtio-gpu.h |  1 +
 hw/display/virtio-gpu.c        |  5 +++++
 hw/display/virtio-vga.c        | 11 +++++++++++
 3 files changed, 17 insertions(+)

diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index 9780f755ef..d0321672f4 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -125,6 +125,7 @@ typedef struct VirtIOGPU {
         uint32_t bytes_3d;
     } stats;
 
+    void (*disable_scanout)(struct VirtIOGPU *g, int scanout_id);
     Error *migration_blocker;
 } VirtIOGPU;
 
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index ec366f4c35..3ddd29c0de 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -421,6 +421,11 @@ static void virtio_gpu_disable_scanout(VirtIOGPU *g, int scanout_id)
                                          scanout->height ?: 480,
                                          "Guest disabled display.");
     }
+
+    if (g->disable_scanout) {
+        g->disable_scanout(g, scanout_id);
+    }
+
     dpy_gfx_replace_surface(scanout->con, ds);
     scanout->resource_id = 0;
     scanout->ds = NULL;
diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
index 2b36f2899a..672b7f9ce2 100644
--- a/hw/display/virtio-vga.c
+++ b/hw/display/virtio-vga.c
@@ -75,6 +75,16 @@ static void virtio_vga_gl_block(void *opaque, bool block)
     }
 }
 
+static void virtio_vga_disable_scanout(VirtIOGPU *g, int scanout_id)
+{
+    VirtIOVGA *vvga = container_of(g, VirtIOVGA, vdev);
+
+    if (scanout_id == 0) {
+        /* reset surface if needed */
+        vvga->vga.graphic_mode = -1;
+    }
+}
+
 static const GraphicHwOps virtio_vga_ops = {
     .invalidate = virtio_vga_invalidate_display,
     .gfx_update = virtio_vga_update_display,
@@ -156,6 +166,7 @@ static void virtio_vga_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
                                  vvga->vga_mrs, true);
 
     vga->con = g->scanout[0].con;
+    g->disable_scanout = virtio_vga_disable_scanout;
     graphic_console_set_hwops(vga->con, &virtio_vga_ops, vvga);
 
     for (i = 0; i < g->conf.max_outputs; i++) {
-- 
2.18.0.547.g1d89318c48

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Stefan Berger]

On 08/03/2018 11:32 AM, Marc-André Lureau wrote:
> With vga=775 on the Linux command line a first boot of the VM running
> Linux works fine. After a warm reboot it crashes during Linux boot.
>
> Before that, valgrind points out bad memory write to console
> surface. The VGA code is not aware that virtio-gpu got a message
> surface scanout when the display is disabled. Let's reset VGA graphic
> mode when it is the case, so that a new display surface is created
> when doing further VGA operations.
>
> https://bugs.launchpad.net/qemu/+bug/1784900/
>
> Reported-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Peter Maydell]

On 3 August 2018 at 16:32, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
> With vga=775 on the Linux command line a first boot of the VM running
> Linux works fine. After a warm reboot it crashes during Linux boot.
>
> Before that, valgrind points out bad memory write to console
> surface. The VGA code is not aware that virtio-gpu got a message
> surface scanout when the display is disabled. Let's reset VGA graphic
> mode when it is the case, so that a new display surface is created
> when doing further VGA operations.
>
> https://bugs.launchpad.net/qemu/+bug/1784900/
>
> Reported-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/hw/virtio/virtio-gpu.h |  1 +
>  hw/display/virtio-gpu.c        |  5 +++++
>  hw/display/virtio-vga.c        | 11 +++++++++++
>  3 files changed, 17 insertions(+)
>
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index 9780f755ef..d0321672f4 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -125,6 +125,7 @@ typedef struct VirtIOGPU {
>          uint32_t bytes_3d;
>      } stats;
>
> +    void (*disable_scanout)(struct VirtIOGPU *g, int scanout_id);
>      Error *migration_blocker;
>  } VirtIOGPU;

I guess for a last-minute 3.0 fix this is ok, but it looks
a bit weird to have a function pointer in a device instance
struct, which the user of the device has reached in and
set in order to modify the behaviour of the object...

thanks
-- PMM

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Marc-André Lureau]

On Mon, Aug 6, 2018 at 3:39 PM, Peter Maydell <peter.maydell@linaro.org> wrote:
> On 3 August 2018 at 16:32, Marc-André Lureau
> <marcandre.lureau@redhat.com> wrote:
>> With vga=775 on the Linux command line a first boot of the VM running
>> Linux works fine. After a warm reboot it crashes during Linux boot.
>>
>> Before that, valgrind points out bad memory write to console
>> surface. The VGA code is not aware that virtio-gpu got a message
>> surface scanout when the display is disabled. Let's reset VGA graphic
>> mode when it is the case, so that a new display surface is created
>> when doing further VGA operations.
>>
>> https://bugs.launchpad.net/qemu/+bug/1784900/
>>
>> Reported-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>> ---
>>  include/hw/virtio/virtio-gpu.h |  1 +
>>  hw/display/virtio-gpu.c        |  5 +++++
>>  hw/display/virtio-vga.c        | 11 +++++++++++
>>  3 files changed, 17 insertions(+)
>>
>> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
>> index 9780f755ef..d0321672f4 100644
>> --- a/include/hw/virtio/virtio-gpu.h
>> +++ b/include/hw/virtio/virtio-gpu.h
>> @@ -125,6 +125,7 @@ typedef struct VirtIOGPU {
>>          uint32_t bytes_3d;
>>      } stats;
>>
>> +    void (*disable_scanout)(struct VirtIOGPU *g, int scanout_id);
>>      Error *migration_blocker;
>>  } VirtIOGPU;
>
> I guess for a last-minute 3.0 fix this is ok, but it looks
> a bit weird to have a function pointer in a device instance
> struct, which the user of the device has reached in and
> set in order to modify the behaviour of the object...

It's not much different than pointing to a static const structure with
function pointers (I thought that was unnecessary for just one
function)

We could also have a VirtioGPUClass with virtual methods, and subclass
TYPE_VIRTIO_GPU. Also a bit over-complicated, and conflicting with my
vhost-user-gpu series. So we may eventually get there in 3.1 though.

>
> thanks
> -- PMM

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Peter Maydell]

I think this is now our last bug fix needed for rc4, which ideally
I'd like to tag tomorrow (Tuesday). Is there anybody familiar with
virtio-gpu who could review it?

thanks
-- PMM

On 3 August 2018 at 16:32, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
> With vga=775 on the Linux command line a first boot of the VM running
> Linux works fine. After a warm reboot it crashes during Linux boot.
>
> Before that, valgrind points out bad memory write to console
> surface. The VGA code is not aware that virtio-gpu got a message
> surface scanout when the display is disabled. Let's reset VGA graphic
> mode when it is the case, so that a new display surface is created
> when doing further VGA operations.
>
> https://bugs.launchpad.net/qemu/+bug/1784900/
>
> Reported-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/hw/virtio/virtio-gpu.h |  1 +
>  hw/display/virtio-gpu.c        |  5 +++++
>  hw/display/virtio-vga.c        | 11 +++++++++++
>  3 files changed, 17 insertions(+)
>
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index 9780f755ef..d0321672f4 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -125,6 +125,7 @@ typedef struct VirtIOGPU {
>          uint32_t bytes_3d;
>      } stats;
>
> +    void (*disable_scanout)(struct VirtIOGPU *g, int scanout_id);
>      Error *migration_blocker;
>  } VirtIOGPU;
>
> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
> index ec366f4c35..3ddd29c0de 100644
> --- a/hw/display/virtio-gpu.c
> +++ b/hw/display/virtio-gpu.c
> @@ -421,6 +421,11 @@ static void virtio_gpu_disable_scanout(VirtIOGPU *g, int scanout_id)
>                                           scanout->height ?: 480,
>                                           "Guest disabled display.");
>      }
> +
> +    if (g->disable_scanout) {
> +        g->disable_scanout(g, scanout_id);
> +    }
> +
>      dpy_gfx_replace_surface(scanout->con, ds);
>      scanout->resource_id = 0;
>      scanout->ds = NULL;
> diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
> index 2b36f2899a..672b7f9ce2 100644
> --- a/hw/display/virtio-vga.c
> +++ b/hw/display/virtio-vga.c
> @@ -75,6 +75,16 @@ static void virtio_vga_gl_block(void *opaque, bool block)
>      }
>  }
>
> +static void virtio_vga_disable_scanout(VirtIOGPU *g, int scanout_id)
> +{
> +    VirtIOVGA *vvga = container_of(g, VirtIOVGA, vdev);
> +
> +    if (scanout_id == 0) {
> +        /* reset surface if needed */
> +        vvga->vga.graphic_mode = -1;
> +    }
> +}
> +
>  static const GraphicHwOps virtio_vga_ops = {
>      .invalidate = virtio_vga_invalidate_display,
>      .gfx_update = virtio_vga_update_display,
> @@ -156,6 +166,7 @@ static void virtio_vga_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
>                                   vvga->vga_mrs, true);
>
>      vga->con = g->scanout[0].con;
> +    g->disable_scanout = virtio_vga_disable_scanout;
>      graphic_console_set_hwops(vga->con, &virtio_vga_ops, vvga);
>
>      for (i = 0; i < g->conf.max_outputs; i++) {
> --
> 2.18.0.547.g1d89318c48
>
>

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Michael S. Tsirkin]

On Fri, Aug 03, 2018 at 05:32:35PM +0200, Marc-André Lureau wrote:
> With vga=775 on the Linux command line a first boot of the VM running
> Linux works fine. After a warm reboot it crashes during Linux boot.
> 
> Before that, valgrind points out bad memory write to console
> surface. The VGA code is not aware that virtio-gpu got a message
> surface scanout when the display is disabled. Let's reset VGA graphic
> mode when it is the case, so that a new display surface is created
> when doing further VGA operations.
> 
> https://bugs.launchpad.net/qemu/+bug/1784900/
> 
> Reported-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/hw/virtio/virtio-gpu.h |  1 +
>  hw/display/virtio-gpu.c        |  5 +++++
>  hw/display/virtio-vga.c        | 11 +++++++++++
>  3 files changed, 17 insertions(+)
> 
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index 9780f755ef..d0321672f4 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -125,6 +125,7 @@ typedef struct VirtIOGPU {
>          uint32_t bytes_3d;
>      } stats;
>  
> +    void (*disable_scanout)(struct VirtIOGPU *g, int scanout_id);
>      Error *migration_blocker;
>  } VirtIOGPU;
>  
> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
> index ec366f4c35..3ddd29c0de 100644
> --- a/hw/display/virtio-gpu.c
> +++ b/hw/display/virtio-gpu.c
> @@ -421,6 +421,11 @@ static void virtio_gpu_disable_scanout(VirtIOGPU *g, int scanout_id)
>                                           scanout->height ?: 480,
>                                           "Guest disabled display.");
>      }
> +
> +    if (g->disable_scanout) {
> +        g->disable_scanout(g, scanout_id);
> +    }
> +
>      dpy_gfx_replace_surface(scanout->con, ds);
>      scanout->resource_id = 0;
>      scanout->ds = NULL;
> diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
> index 2b36f2899a..672b7f9ce2 100644
> --- a/hw/display/virtio-vga.c
> +++ b/hw/display/virtio-vga.c
> @@ -75,6 +75,16 @@ static void virtio_vga_gl_block(void *opaque, bool block)
>      }
>  }
>  
> +static void virtio_vga_disable_scanout(VirtIOGPU *g, int scanout_id)
> +{
> +    VirtIOVGA *vvga = container_of(g, VirtIOVGA, vdev);
> +
> +    if (scanout_id == 0) {
> +        /* reset surface if needed */
> +        vvga->vga.graphic_mode = -1;
> +    }
> +}
> +
>  static const GraphicHwOps virtio_vga_ops = {
>      .invalidate = virtio_vga_invalidate_display,
>      .gfx_update = virtio_vga_update_display,

Would it make sense to add
vga_disable_scanout() to hw/display/vga_int.h and
poke at graphic_mode there?

I'll leave the decision to you.

> @@ -156,6 +166,7 @@ static void virtio_vga_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
>                                   vvga->vga_mrs, true);
>  
>      vga->con = g->scanout[0].con;
> +    g->disable_scanout = virtio_vga_disable_scanout;
>      graphic_console_set_hwops(vga->con, &virtio_vga_ops, vvga);
>  
>      for (i = 0; i < g->conf.max_outputs; i++) {

While I really know very little about vga, it seems
like that's the standard way to force full update so


Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

-- 
MST

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Marc-André Lureau]

Hi

On Mon, Aug 6, 2018 at 11:16 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> On Fri, Aug 03, 2018 at 05:32:35PM +0200, Marc-André Lureau wrote:
>> With vga=775 on the Linux command line a first boot of the VM running
>> Linux works fine. After a warm reboot it crashes during Linux boot.
>>
>> Before that, valgrind points out bad memory write to console
>> surface. The VGA code is not aware that virtio-gpu got a message
>> surface scanout when the display is disabled. Let's reset VGA graphic
>> mode when it is the case, so that a new display surface is created
>> when doing further VGA operations.
>>
>> https://bugs.launchpad.net/qemu/+bug/1784900/
>>
>> Reported-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>> ---
>>  include/hw/virtio/virtio-gpu.h |  1 +
>>  hw/display/virtio-gpu.c        |  5 +++++
>>  hw/display/virtio-vga.c        | 11 +++++++++++
>>  3 files changed, 17 insertions(+)
>>
>> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
>> index 9780f755ef..d0321672f4 100644
>> --- a/include/hw/virtio/virtio-gpu.h
>> +++ b/include/hw/virtio/virtio-gpu.h
>> @@ -125,6 +125,7 @@ typedef struct VirtIOGPU {
>>          uint32_t bytes_3d;
>>      } stats;
>>
>> +    void (*disable_scanout)(struct VirtIOGPU *g, int scanout_id);
>>      Error *migration_blocker;
>>  } VirtIOGPU;
>>
>> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
>> index ec366f4c35..3ddd29c0de 100644
>> --- a/hw/display/virtio-gpu.c
>> +++ b/hw/display/virtio-gpu.c
>> @@ -421,6 +421,11 @@ static void virtio_gpu_disable_scanout(VirtIOGPU *g, int scanout_id)
>>                                           scanout->height ?: 480,
>>                                           "Guest disabled display.");
>>      }
>> +
>> +    if (g->disable_scanout) {
>> +        g->disable_scanout(g, scanout_id);
>> +    }
>> +
>>      dpy_gfx_replace_surface(scanout->con, ds);
>>      scanout->resource_id = 0;
>>      scanout->ds = NULL;
>> diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
>> index 2b36f2899a..672b7f9ce2 100644
>> --- a/hw/display/virtio-vga.c
>> +++ b/hw/display/virtio-vga.c
>> @@ -75,6 +75,16 @@ static void virtio_vga_gl_block(void *opaque, bool block)
>>      }
>>  }
>>
>> +static void virtio_vga_disable_scanout(VirtIOGPU *g, int scanout_id)
>> +{
>> +    VirtIOVGA *vvga = container_of(g, VirtIOVGA, vdev);
>> +
>> +    if (scanout_id == 0) {
>> +        /* reset surface if needed */
>> +        vvga->vga.graphic_mode = -1;
>> +    }
>> +}
>> +
>>  static const GraphicHwOps virtio_vga_ops = {
>>      .invalidate = virtio_vga_invalidate_display,
>>      .gfx_update = virtio_vga_update_display,
>
> Would it make sense to add
> vga_disable_scanout() to hw/display/vga_int.h and
> poke at graphic_mode there?
>
> I'll leave the decision to you.

If Gerd doesn't chime in before RC4, I suggest to take that version.
He might want to update it or take a different approach post 3.0.

>
>> @@ -156,6 +166,7 @@ static void virtio_vga_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
>>                                   vvga->vga_mrs, true);
>>
>>      vga->con = g->scanout[0].con;
>> +    g->disable_scanout = virtio_vga_disable_scanout;
>>      graphic_console_set_hwops(vga->con, &virtio_vga_ops, vvga);
>>
>>      for (i = 0; i < g->conf.max_outputs; i++) {
>
> While I really know very little about vga, it seems
> like that's the standard way to force full update so
>
>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

thanks



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Gerd Hoffmann]

On Fri, Aug 03, 2018 at 05:32:35PM +0200, Marc-André Lureau wrote:
> With vga=775 on the Linux command line a first boot of the VM running
> Linux works fine. After a warm reboot it crashes during Linux boot.
> 
> Before that, valgrind points out bad memory write to console
> surface. The VGA code is not aware that virtio-gpu got a message
> surface scanout when the display is disabled. Let's reset VGA graphic
> mode when it is the case, so that a new display surface is created
> when doing further VGA operations.

I guess we should simply call vga_common_reset() in virtio_vga_reset()
instead, can you try that?

thanks,
  Gerd

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Marc-André Lureau]

Hi

On Tue, Aug 7, 2018 at 2:55 PM, Gerd Hoffmann <kraxel@redhat.com> wrote:
> On Fri, Aug 03, 2018 at 05:32:35PM +0200, Marc-André Lureau wrote:
>> With vga=775 on the Linux command line a first boot of the VM running
>> Linux works fine. After a warm reboot it crashes during Linux boot.
>>
>> Before that, valgrind points out bad memory write to console
>> surface. The VGA code is not aware that virtio-gpu got a message
>> surface scanout when the display is disabled. Let's reset VGA graphic
>> mode when it is the case, so that a new display surface is created
>> when doing further VGA operations.
>
> I guess we should simply call vga_common_reset() in virtio_vga_reset()
> instead, can you try that?
>
Yes I tried, and it still fails. However I think the call is missing
and I was planning to send it for 3.1 later, since I don't think it's
RC material.
The ordering of events is not completely obvious to me, but it's still
crashing/corrupting memory after the reset occurs. The scanout get's
disable after it iirc.


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Gerd Hoffmann]

On Tue, Aug 07, 2018 at 03:02:49PM +0200, Marc-André Lureau wrote:
> Hi
> 
> On Tue, Aug 7, 2018 at 2:55 PM, Gerd Hoffmann <kraxel@redhat.com> wrote:
> > On Fri, Aug 03, 2018 at 05:32:35PM +0200, Marc-André Lureau wrote:
> >> With vga=775 on the Linux command line a first boot of the VM running
> >> Linux works fine. After a warm reboot it crashes during Linux boot.
> >>
> >> Before that, valgrind points out bad memory write to console
> >> surface. The VGA code is not aware that virtio-gpu got a message
> >> surface scanout when the display is disabled. Let's reset VGA graphic
> >> mode when it is the case, so that a new display surface is created
> >> when doing further VGA operations.
> >
> > I guess we should simply call vga_common_reset() in virtio_vga_reset()
> > instead, can you try that?
> >
> Yes I tried, and it still fails. However I think the call is missing
> and I was planning to send it for 3.1 later, since I don't think it's
> RC material.
> The ordering of events is not completely obvious to me, but it's still
> crashing/corrupting memory after the reset occurs. The scanout get's
> disable after it iirc.

Ok, lets go with this patch for -rc4 and figure the reset issues later.
It is correct, even though I think there must be a simpler way to do it.
When we have a better fix we can revert it.

Peter, can you apply it directly?

Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>

thanks,
  Gerd

Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Peter Maydell]

On 7 August 2018 at 14:41, Gerd Hoffmann <kraxel@redhat.com> wrote:
> On Tue, Aug 07, 2018 at 03:02:49PM +0200, Marc-André Lureau wrote:
>> Hi
>>
>> On Tue, Aug 7, 2018 at 2:55 PM, Gerd Hoffmann <kraxel@redhat.com> wrote:
>> > On Fri, Aug 03, 2018 at 05:32:35PM +0200, Marc-André Lureau wrote:
>> >> With vga=775 on the Linux command line a first boot of the VM running
>> >> Linux works fine. After a warm reboot it crashes during Linux boot.
>> >>
>> >> Before that, valgrind points out bad memory write to console
>> >> surface. The VGA code is not aware that virtio-gpu got a message
>> >> surface scanout when the display is disabled. Let's reset VGA graphic
>> >> mode when it is the case, so that a new display surface is created
>> >> when doing further VGA operations.
>> >
>> > I guess we should simply call vga_common_reset() in virtio_vga_reset()
>> > instead, can you try that?
>> >
>> Yes I tried, and it still fails. However I think the call is missing
>> and I was planning to send it for 3.1 later, since I don't think it's
>> RC material.
>> The ordering of events is not completely obvious to me, but it's still
>> crashing/corrupting memory after the reset occurs. The scanout get's
>> disable after it iirc.
>
> Ok, lets go with this patch for -rc4 and figure the reset issues later.
> It is correct, even though I think there must be a simpler way to do it.
> When we have a better fix we can revert it.
>
> Peter, can you apply it directly?
>
> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>

Applied to master, thanks.

-- PMM