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[Qemu-devel] [PATCH] vhost: skip ROM sections
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PATCH] vhost: skip ROM sections |
Date: |
Tue, 24 Jan 2017 19:11:09 +0200 |
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 <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
---
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)
--
MST
- [Qemu-devel] [PATCH] vhost: skip ROM sections,
Michael S. Tsirkin <=