| Message ID | 1485277734-16871-1-git-send-email-mst@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 24/01/2017 18:11, Michael S. Tsirkin wrote: > vhost does not support RO protections on memory at the moment - adding > ROMs would mean that e.g. a buggy guest might change them in-memory - a > condition from which guest reset does not recover. Not nice. > > We also definitely don't want to try logging writes into ROMs - in > particular guests set very high addresses for ROM BARs so logging these > writes would waste a lot of memory. With phys address in the 32T range > we would need 1Gbyte sized log - scanning it would take ages, and > allocating such huge amount of log memory was also reported to fail on > powerpc. > > Maybe ROMs could be supported with the iotlb variant - > not sure, but there seems to be no good reason for virtio > to try to do DMA from ROM. So let's just skip ROM memory. > > Suggested-by: Laurent Vivier <lvivier@redhat.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Laurent Vivier <lvivier@redhat.com> Tested-by: Laurent Vivier <lvivier@redhat.com> > --- > hw/virtio/vhost.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index 9cacf55..94b8c4a 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -612,7 +612,8 @@ static void vhost_set_memory(MemoryListener *listener, > > static bool vhost_section(MemoryRegionSection *section) > { > - return memory_region_is_ram(section->mr); > + return memory_region_is_ram(section->mr) && > + !memory_region_is_rom(section->mr); > } > > static void vhost_begin(MemoryListener *listener) >
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 9cacf55..94b8c4a 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -612,7 +612,8 @@ static void vhost_set_memory(MemoryListener *listener, static bool vhost_section(MemoryRegionSection *section) { - return memory_region_is_ram(section->mr); + return memory_region_is_ram(section->mr) && + !memory_region_is_rom(section->mr); } static void vhost_begin(MemoryListener *listener)
vhost does not support RO protections on memory at the moment - adding ROMs would mean that e.g. a buggy guest might change them in-memory - a condition from which guest reset does not recover. Not nice. We also definitely don't want to try logging writes into ROMs - in particular guests set very high addresses for ROM BARs so logging these writes would waste a lot of memory. With phys address in the 32T range we would need 1Gbyte sized log - scanning it would take ages, and allocating such huge amount of log memory was also reported to fail on powerpc. Maybe ROMs could be supported with the iotlb variant - not sure, but there seems to be no good reason for virtio to try to do DMA from ROM. So let's just skip ROM memory. Suggested-by: Laurent Vivier <lvivier@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- hw/virtio/vhost.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)