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[PATCH v3 3/9] vfio: add quirk device write method

P J P posted 9 patches 5 years, 3 months ago
Maintainers: Alex Williamson <alex.williamson@redhat.com>, David Gibson <david@gibson.dropbear.id.au>, Joel Stanley <joel@jms.id.au>, Peter Maydell <peter.maydell@linaro.org>, Andrey Smirnov <andrew.smirnov@gmail.com>, "Hervé Poussineau" <hpoussin@reactos.org>
There is a newer version of this series
[PATCH v3 3/9] vfio: add quirk device write method
Posted by P J P 5 years, 3 months ago 
From: Prasad J Pandit <pjp@fedoraproject.org>

Add vfio quirk device mmio write method to avoid NULL pointer
dereference issue.

Reported-by: Lei Sun <slei.casper@gmail.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/vfio/pci-quirks.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Update v3: Add Reviewed-by: ...
  -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg09406.html

diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index d304c81148..cc6d5dbc23 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -14,6 +14,7 @@
 #include "config-devices.h"
 #include "exec/memop.h"
 #include "qemu/units.h"
+#include "qemu/log.h"
 #include "qemu/error-report.h"
 #include "qemu/main-loop.h"
 #include "qemu/module.h"
@@ -264,8 +265,15 @@ static uint64_t vfio_ati_3c3_quirk_read(void *opaque,
     return data;
 }
 
+static void vfio_ati_3c3_quirk_write(void *opaque, hwaddr addr,
+                                        uint64_t data, unsigned size)
+{
+    qemu_log_mask(LOG_GUEST_ERROR, "%s not implemented\n", __func__);
+}
+
 static const MemoryRegionOps vfio_ati_3c3_quirk = {
     .read = vfio_ati_3c3_quirk_read,
+    .write = vfio_ati_3c3_quirk_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
-- 
2.26.2
Re: [PATCH v3 3/9] vfio: add quirk device write method
Posted by Peter Maydell 5 years, 2 months ago 
On Tue, 30 Jun 2020 at 13:30, P J P <ppandit@redhat.com> wrote:
>
> From: Prasad J Pandit <pjp@fedoraproject.org>
>
> Add vfio quirk device mmio write method to avoid NULL pointer
> dereference issue.
>
> Reported-by: Lei Sun <slei.casper@gmail.com>
> Reviewed-by: Li Qiang <liq3ea@gmail.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>  hw/vfio/pci-quirks.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> Update v3: Add Reviewed-by: ...
>   -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg09406.html
>
> diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
> index d304c81148..cc6d5dbc23 100644
> --- a/hw/vfio/pci-quirks.c
> +++ b/hw/vfio/pci-quirks.c
> @@ -14,6 +14,7 @@
>  #include "config-devices.h"
>  #include "exec/memop.h"
>  #include "qemu/units.h"
> +#include "qemu/log.h"
>  #include "qemu/error-report.h"
>  #include "qemu/main-loop.h"
>  #include "qemu/module.h"
> @@ -264,8 +265,15 @@ static uint64_t vfio_ati_3c3_quirk_read(void *opaque,
>      return data;
>  }
>
> +static void vfio_ati_3c3_quirk_write(void *opaque, hwaddr addr,
> +                                        uint64_t data, unsigned size)
> +{
> +    qemu_log_mask(LOG_GUEST_ERROR, "%s not implemented\n", __func__);
> +}
> +
>  static const MemoryRegionOps vfio_ati_3c3_quirk = {
>      .read = vfio_ati_3c3_quirk_read,
> +    .write = vfio_ati_3c3_quirk_write,
>      .endianness = DEVICE_LITTLE_ENDIAN,
>  };


Alex (Williamson) -- as the vfio maintainer, do you have a view
on whether we should be logging write accesses to port 0x3c3
here as guest-errors or unimplemented-QEMU-functionality?

Guest-error seems plausible to me, anyway.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM
Re: [PATCH v3 3/9] vfio: add quirk device write method
Posted by Alex Williamson 5 years, 2 months ago 
On Thu, 16 Jul 2020 18:46:33 +0100
Peter Maydell <peter.maydell@linaro.org> wrote:

> On Tue, 30 Jun 2020 at 13:30, P J P <ppandit@redhat.com> wrote:
> >
> > From: Prasad J Pandit <pjp@fedoraproject.org>
> >
> > Add vfio quirk device mmio write method to avoid NULL pointer
> > dereference issue.
> >
> > Reported-by: Lei Sun <slei.casper@gmail.com>
> > Reviewed-by: Li Qiang <liq3ea@gmail.com>
> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> > ---
> >  hw/vfio/pci-quirks.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > Update v3: Add Reviewed-by: ...  
> >   -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg09406.html  
> >
> > diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
> > index d304c81148..cc6d5dbc23 100644
> > --- a/hw/vfio/pci-quirks.c
> > +++ b/hw/vfio/pci-quirks.c
> > @@ -14,6 +14,7 @@
> >  #include "config-devices.h"
> >  #include "exec/memop.h"
> >  #include "qemu/units.h"
> > +#include "qemu/log.h"
> >  #include "qemu/error-report.h"
> >  #include "qemu/main-loop.h"
> >  #include "qemu/module.h"
> > @@ -264,8 +265,15 @@ static uint64_t vfio_ati_3c3_quirk_read(void *opaque,
> >      return data;
> >  }
> >
> > +static void vfio_ati_3c3_quirk_write(void *opaque, hwaddr addr,
> > +                                        uint64_t data, unsigned size)
> > +{
> > +    qemu_log_mask(LOG_GUEST_ERROR, "%s not implemented\n", __func__);
> > +}
> > +
> >  static const MemoryRegionOps vfio_ati_3c3_quirk = {
> >      .read = vfio_ati_3c3_quirk_read,
> > +    .write = vfio_ati_3c3_quirk_write,
> >      .endianness = DEVICE_LITTLE_ENDIAN,
> >  };  
> 
> 
> Alex (Williamson) -- as the vfio maintainer, do you have a view
> on whether we should be logging write accesses to port 0x3c3
> here as guest-errors or unimplemented-QEMU-functionality?
> 
> Guest-error seems plausible to me, anyway.

I believe the intention was that writes would be dropped, so if this
generates logging that is going to cause users to file bugs, that would
be undesirable.  Thanks,

Alex
Re: [PATCH v3 3/9] vfio: add quirk device write method
Posted by Peter Maydell 5 years, 2 months ago 
On Fri, 17 Jul 2020 at 16:54, Alex Williamson
<alex.williamson@redhat.com> wrote:
>
> On Thu, 16 Jul 2020 18:46:33 +0100
> Peter Maydell <peter.maydell@linaro.org> wrote:
>
> > Alex (Williamson) -- as the vfio maintainer, do you have a view
> > on whether we should be logging write accesses to port 0x3c3
> > here as guest-errors or unimplemented-QEMU-functionality?
> >
> > Guest-error seems plausible to me, anyway.
>
> I believe the intention was that writes would be dropped, so if this
> generates logging that is going to cause users to file bugs, that would
> be undesirable.  Thanks,

It will only log if the user explicitly turns on "log things the
guest does which are bugs in it, like writing to read-only
registers" (with the '-d guest_errors' option).

thanks
-- PMM
Re: [PATCH v3 3/9] vfio: add quirk device write method
Posted by Alex Williamson 5 years, 2 months ago 
On Fri, 17 Jul 2020 16:57:40 +0100
Peter Maydell <peter.maydell@linaro.org> wrote:

> On Fri, 17 Jul 2020 at 16:54, Alex Williamson
> <alex.williamson@redhat.com> wrote:
> >
> > On Thu, 16 Jul 2020 18:46:33 +0100
> > Peter Maydell <peter.maydell@linaro.org> wrote:
> >  
> > > Alex (Williamson) -- as the vfio maintainer, do you have a view
> > > on whether we should be logging write accesses to port 0x3c3
> > > here as guest-errors or unimplemented-QEMU-functionality?
> > >
> > > Guest-error seems plausible to me, anyway.  
> >
> > I believe the intention was that writes would be dropped, so if this
> > generates logging that is going to cause users to file bugs, that would
> > be undesirable.  Thanks,  
> 
> It will only log if the user explicitly turns on "log things the
> guest does which are bugs in it, like writing to read-only
> registers" (with the '-d guest_errors' option).

IIRC, this quirk is based on observation more so than an actual spec,
so whether a log of such an event is interpreted as a guest error or an
emulation error might be up for debate.  Aside from that nit, and lack
of bandwidth to research how hardware handles writes,

Acked-by: Alex Williamson <alex.williamson@redhat.com>

Thanks,
Alex

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