88 lines
3.4 KiB
Diff
88 lines
3.4 KiB
Diff
From 354946f1e5fee0a69282bdf284c969b03a78a53e Mon Sep 17 00:00:00 2001
|
|
From: Jon Maloy <jmaloy@redhat.com>
|
|
Date: Wed, 13 Jan 2021 00:42:23 -0500
|
|
Subject: [PATCH 15/17] memory: clamp cached translation in case it points to
|
|
an MMIO region
|
|
|
|
RH-Author: Jon Maloy <jmaloy@redhat.com>
|
|
Message-id: <20210113004223.871394-2-jmaloy@redhat.com>
|
|
Patchwork-id: 100618
|
|
O-Subject: [RHEL-8.4.0 qemu-kvm PATCH 1/1] memory: clamp cached translation in case it points to an MMIO region
|
|
Bugzilla: 1904393
|
|
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
|
|
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
|
|
RH-Acked-by: Thomas Huth <thuth@redhat.com>
|
|
|
|
From: Paolo Bonzini <pbonzini@redhat.com>
|
|
|
|
In using the address_space_translate_internal API, address_space_cache_init
|
|
forgot one piece of advice that can be found in the code for
|
|
address_space_translate_internal:
|
|
|
|
/* MMIO registers can be expected to perform full-width accesses based only
|
|
* on their address, without considering adjacent registers that could
|
|
* decode to completely different MemoryRegions. When such registers
|
|
* exist (e.g. I/O ports 0xcf8 and 0xcf9 on most PC chipsets), MMIO
|
|
* regions overlap wildly. For this reason we cannot clamp the accesses
|
|
* here.
|
|
*
|
|
* If the length is small (as is the case for address_space_ldl/stl),
|
|
* everything works fine. If the incoming length is large, however,
|
|
* the caller really has to do the clamping through memory_access_size.
|
|
*/
|
|
|
|
address_space_cache_init is exactly one such case where "the incoming length
|
|
is large", therefore we need to clamp the resulting length---not to
|
|
memory_access_size though, since we are not doing an access yet, but to
|
|
the size of the resulting section. This ensures that subsequent accesses
|
|
to the cached MemoryRegionSection will be in range.
|
|
|
|
With this patch, the enclosed testcase notices that the used ring does
|
|
not fit into the MSI-X table and prints a "qemu-system-x86_64: Cannot map used"
|
|
error.
|
|
|
|
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
|
|
|
|
(cherry picked from 4bfb024bc76973d40a359476dc0291f46e435442)
|
|
- Manually applied to file exec.c, where the code to correct
|
|
is located in this version.
|
|
- Skipped the fuzzing test part, which is hard to apply on this code.
|
|
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
|
|
|
|
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
|
|
---
|
|
exec.c | 10 ++++++++++
|
|
1 file changed, 10 insertions(+)
|
|
|
|
diff --git a/exec.c b/exec.c
|
|
index ffdb5185353..09ed0cfc756 100644
|
|
--- a/exec.c
|
|
+++ b/exec.c
|
|
@@ -3620,6 +3620,7 @@ int64_t address_space_cache_init(MemoryRegionCache *cache,
|
|
AddressSpaceDispatch *d;
|
|
hwaddr l;
|
|
MemoryRegion *mr;
|
|
+ Int128 diff;
|
|
|
|
assert(len > 0);
|
|
|
|
@@ -3628,6 +3629,15 @@ int64_t address_space_cache_init(MemoryRegionCache *cache,
|
|
d = flatview_to_dispatch(cache->fv);
|
|
cache->mrs = *address_space_translate_internal(d, addr, &cache->xlat, &l, true);
|
|
|
|
+ /*
|
|
+ * cache->xlat is now relative to cache->mrs.mr, not to the section itself.
|
|
+ * Take that into account to compute how many bytes are there between
|
|
+ * cache->xlat and the end of the section.
|
|
+ */
|
|
+ diff = int128_sub(cache->mrs.size,
|
|
+ int128_make64(cache->xlat - cache->mrs.offset_within_region));
|
|
+ l = int128_get64(int128_min(diff, int128_make64(l)));
|
|
+
|
|
mr = cache->mrs.mr;
|
|
memory_region_ref(mr);
|
|
if (memory_access_is_direct(mr, is_write)) {
|
|
--
|
|
2.27.0
|
|
|