File 0083-exec-do-not-clamp-accesses-to-MMIO-.patch of Package qemu.10254

Overview Repositories Revisions Requests Users Attributes Meta

File 0083-exec-do-not-clamp-accesses-to-MMIO-.patch of Package qemu.10254

From c5ac2044f4634549918f1703cdd44f9f1324b7ee Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 17 Jun 2015 10:40:27 +0200
Subject: [PATCH] exec: do not clamp accesses to MMIO regions
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

It is common for MMIO registers to overlap, for example a 4 byte register
at 0xcf8 (totally random choice... :)) and a 1 byte register at 0xcf9.
If these registers are implemented via separate MemoryRegions, it is
wrong to clamp the accesses as the value written would be truncated.

Hence for these regions the effects of commit 23820db (exec: Respect
as_translate_internal length clamp, 2015-03-16, previously applied as
commit c3c1bb99) must be skipped.

Tested-by: Hervé Poussineau <hpoussin@reactos.org>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 965eb2fcdfe919ecced6c34803535ad32dc1249c)
[BR: support patch for BSC#969122]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 exec.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/exec.c b/exec.c
index 692d1cca5f..c25ef68815 100644
--- a/exec.c
+++ b/exec.c
@@ -347,6 +347,7 @@ address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *x
                                  hwaddr *plen, bool resolve_subpage)
 {
     MemoryRegionSection *section;
+    MemoryRegion *mr;
     Int128 diff;
 
     section = address_space_lookup_region(d, addr, resolve_subpage);
@@ -356,8 +357,11 @@ address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *x
     /* Compute offset within MemoryRegion */
     *xlat = addr + section->offset_within_region;
 
-    diff = int128_sub(section->mr->size, int128_make64(addr));
-    *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
+    mr = section->mr;
+    if (memory_region_is_ram(mr)) {
+        diff = int128_sub(mr->size, int128_make64(addr));
+        *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
+    }
     return section;
 }

Places

File 0083-exec-do-not-clamp-accesses-to-MMIO-.patch of Package qemu.10254

Places