patch 1 modifies handler of ram device memory regions to drop guest writes
to read-only ram device memory regions

patch 2 modifies handler of non-mmap'd read-only vfio regions to drop guest
writes to those regions 

patch 3 let mmap'd read-only vfio regions be able to generate vmexit for
guest write. so, without patch 1, host qemu would crash on guest write to
this read-only region. with patch 1, host qemu would drop the writes.

Yan Zhao (3):
  memory: drop guest writes to read-only ram device regions
  hw/vfio: drop guest writes to ro regions
  hw/vfio: let read-only flag take effect for mmap'd regions

 hw/vfio/common.c     | 12 +++++++++++-
 hw/vfio/trace-events |  2 +-
 memory.c             |  6 +++++-
 trace-events         |  2 +-
 4 files changed, 18 insertions(+), 4 deletions(-)

-- 
2.17.1

On Fri, 3 Apr 2020 at 09:13, Yan Zhao <yan.y.zhao@intel.com> wrote:
>
> patch 1 modifies handler of ram device memory regions to drop guest writes
> to read-only ram device memory regions
>
> patch 2 modifies handler of non-mmap'd read-only vfio regions to drop guest
> writes to those regions
>
> patch 3 let mmap'd read-only vfio regions be able to generate vmexit for
> guest write. so, without patch 1, host qemu would crash on guest write to
> this read-only region. with patch 1, host qemu would drop the writes.

Just FYI, there seems to be a minor clock or timezone issue with
however you're sending these emails: the Date header you
sent reads "Date: Fri, 3 Apr 2020 16:56:57 +0000" but that
time in the UTC +0000 timezone is (as I write this) still several
hours in the future. This isn't a big deal but you probably want
to look into fixing it.

(Noticed because the wrong-date makes your patches stick to
the top of the https://patchew.org/QEMU/ list even after other
patches arrive after them.)

thanks
-- PMM

On Fri, Apr 03, 2020 at 08:53:12PM +0800, Peter Maydell wrote:
> On Fri, 3 Apr 2020 at 09:13, Yan Zhao <yan.y.zhao@intel.com> wrote:
> >
> > patch 1 modifies handler of ram device memory regions to drop guest writes
> > to read-only ram device memory regions
> >
> > patch 2 modifies handler of non-mmap'd read-only vfio regions to drop guest
> > writes to those regions
> >
> > patch 3 let mmap'd read-only vfio regions be able to generate vmexit for
> > guest write. so, without patch 1, host qemu would crash on guest write to
> > this read-only region. with patch 1, host qemu would drop the writes.
> 
> Just FYI, there seems to be a minor clock or timezone issue with
> however you're sending these emails: the Date header you
> sent reads "Date: Fri, 3 Apr 2020 16:56:57 +0000" but that
> time in the UTC +0000 timezone is (as I write this) still several
> hours in the future. This isn't a big deal but you probably want
> to look into fixing it.
> 
> (Noticed because the wrong-date makes your patches stick to
> the top of the https://patchew.org/QEMU/ list even after other
> patches arrive after them.)
>
thanks for informing of it! will pay attention to it.
Thanks
Yan

patch 1 modifies handler of ram device memory regions to drop guest writes
to read-only ram device memory regions

patch 2 modifies handler of non-mmap'd read-only vfio regions to drop guest
writes to those regions 

patch 3 let mmap'd read-only vfio regions be able to generate vmexit for
guest write. so, without patch 1, host qemu would crash on guest write to
this read-only region. with patch 1, host qemu would drop the writes.

Changelog:
v2:
-split one big patches into smaller ones (Philippe)
-modify existing trace to record guest writes to read-only memory (Alex)
-modify vfio_region_write() to drop guest writes to non-mmap'd read-only
 region (Alex)

Yan Zhao (3):
  memory: drop guest writes to read-only ram device regions
  hw/vfio: drop guest writes to ro regions
  hw/vfio: let read-only flag take effect for mmap'd regions

 hw/vfio/common.c     | 12 +++++++++++-
 hw/vfio/trace-events |  2 +-
 memory.c             |  6 +++++-
 trace-events         |  2 +-
 4 files changed, 18 insertions(+), 4 deletions(-)

-- 
2.17.1

Forgot the changelog, so sent this patch 0/3 again.
sorry about that.

On Sat, Apr 04, 2020 at 01:08:23AM +0800, Zhao, Yan Y wrote:
> patch 1 modifies handler of ram device memory regions to drop guest writes
> to read-only ram device memory regions
> 
> patch 2 modifies handler of non-mmap'd read-only vfio regions to drop guest
> writes to those regions 
> 
> patch 3 let mmap'd read-only vfio regions be able to generate vmexit for
> guest write. so, without patch 1, host qemu would crash on guest write to
> this read-only region. with patch 1, host qemu would drop the writes.
> 
> Changelog:
> v2:
> -split one big patches into smaller ones (Philippe)
> -modify existing trace to record guest writes to read-only memory (Alex)
> -modify vfio_region_write() to drop guest writes to non-mmap'd read-only
>  region (Alex)
> 
> Yan Zhao (3):
>   memory: drop guest writes to read-only ram device regions
>   hw/vfio: drop guest writes to ro regions
>   hw/vfio: let read-only flag take effect for mmap'd regions
> 
>  hw/vfio/common.c     | 12 +++++++++++-
>  hw/vfio/trace-events |  2 +-
>  memory.c             |  6 +++++-
>  trace-events         |  2 +-
>  4 files changed, 18 insertions(+), 4 deletions(-)
> 
> -- 
> 2.17.1
>