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authorPaolo Bonzini <pbonzini@redhat.com>2014-02-07 15:47:46 +0100
committerPeter Maydell <peter.maydell@linaro.org>2014-02-10 18:10:43 +0000
commita87f39543a9259f671c5413723311180ee2ad2a8 (patch)
tree53c42691028566ae1d64a4a911b151d97c55ad35 /exec.c
parent1f6b12f75f2c22f861d0202374033a7594c91707 (diff)
downloadqemu-arm-a87f39543a9259f671c5413723311180ee2ad2a8.tar.gz
memory: fix limiting of translation at a page boundary
Commit 360e607 (address_space_translate: do not cross page boundaries, 2014-01-30) broke MMIO accesses in cases where the section is shorter than the full register width. This can happen for example with the Bochs DISPI registers, which are 16 bits wide but have only a 1-byte long MemoryRegion (if you write to the "second byte" of the register your access is discarded; it doesn't write only to half of the register). Restrict the action of commit 360e607 to direct RAM accesses. This is enough for Xen, since MMIO will not go through the mapcache. Reported-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'exec.c')
-rw-r--r--exec.c35
1 files changed, 19 insertions, 16 deletions
diff --git a/exec.c b/exec.c
index 9ad0a4b045..be93ebb505 100644
--- a/exec.c
+++ b/exec.c
@@ -325,7 +325,7 @@ address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *x
hwaddr *plen, bool resolve_subpage)
{
MemoryRegionSection *section;
- Int128 diff, diff_page;
+ Int128 diff;
section = address_space_lookup_region(d, addr, resolve_subpage);
/* Compute offset within MemoryRegionSection */
@@ -334,13 +334,23 @@ address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *x
/* Compute offset within MemoryRegion */
*xlat = addr + section->offset_within_region;
- diff_page = int128_make64(((addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE) - addr);
diff = int128_sub(section->mr->size, int128_make64(addr));
- diff = int128_min(diff, diff_page);
*plen = int128_get64(int128_min(diff, int128_make64(*plen)));
return section;
}
+static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
+{
+ if (memory_region_is_ram(mr)) {
+ return !(is_write && mr->readonly);
+ }
+ if (memory_region_is_romd(mr)) {
+ return !is_write;
+ }
+
+ return false;
+}
+
MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
hwaddr *xlat, hwaddr *plen,
bool is_write)
@@ -351,7 +361,7 @@ MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
hwaddr len = *plen;
for (;;) {
- section = address_space_translate_internal(as->dispatch, addr, &addr, &len, true);
+ section = address_space_translate_internal(as->dispatch, addr, &addr, plen, true);
mr = section->mr;
if (!mr->iommu_ops) {
@@ -370,6 +380,11 @@ MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
as = iotlb.target_as;
}
+ if (memory_access_is_direct(mr, is_write)) {
+ hwaddr page = ((addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE) - addr;
+ len = MIN(page, len);
+ }
+
*plen = len;
*xlat = addr;
return mr;
@@ -1925,18 +1940,6 @@ static void invalidate_and_set_dirty(hwaddr addr,
xen_modified_memory(addr, length);
}
-static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
-{
- if (memory_region_is_ram(mr)) {
- return !(is_write && mr->readonly);
- }
- if (memory_region_is_romd(mr)) {
- return !is_write;
- }
-
- return false;
-}
-
static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr)
{
unsigned access_size_max = mr->ops->valid.max_access_size;