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qemu-testsuite.7646
0252-xen-mapcache-store-dma-information-.patch
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File 0252-xen-mapcache-store-dma-information-.patch of Package qemu-testsuite.7646
From 81bfb405d3883ac5fd696f5674492c4a375ff3e9 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini <sstabellini@kernel.org> Date: Wed, 3 May 2017 14:00:35 -0700 Subject: [PATCH] xen/mapcache: store dma information in revmapcache entries for debugging The Xen mapcache is able to create long term mappings, they are called "locked" mappings. The third parameter of the xen_map_cache call specifies if a mapping is a "locked" mapping. >From the QEMU point of view there are two kinds of long term mappings: [a] device memory mappings, such as option roms and video memory [b] dma mappings, created by dma_memory_map & friends After certain operations, ballooning a VM in particular, Xen asks QEMU kindly to destroy all mappings. However, certainly [a] mappings are present and cannot be removed. That's not a problem as they are not affected by balloonning. The *real* problem is that if there are any mappings of type [b], any outstanding dma operations could fail. This is a known shortcoming. In other words, when Xen asks QEMU to destroy all mappings, it is an error if any [b] mappings exist. However today we have no way of distinguishing [a] from [b]. Because of that, we cannot even print a decent warning. This patch introduces a new "dma" bool field to MapCacheRev entires, to remember if a given mapping is for dma or is a long term device memory mapping. When xen_invalidate_map_cache is called, we print a warning if any [b] mappings exist. We ignore [a] mappings. Mappings created by qemu_map_ram_ptr are assumed to be [a], while mappings created by address_space_map->qemu_ram_ptr_length are assumed to be [b]. The goal of the patch is to make debugging and system understanding easier. Signed-off-by: Stefano Stabellini <sstabellini@kernel.org> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Anthony PERARD <anthony.perard@citrix.com> (cherry picked from commit 1ff7c5986a515d2d936eba026ff19947bbc7cb92) [BR: BSC#1048902 BSC#1069178 CVE-2017-11334 (additional fix needed for orig issue)] Signed-off-by: Bruce Rogers <brogers@suse.com> --- exec.c | 8 ++++---- include/sysemu/xen-mapcache.h | 5 +++-- xen-mapcache.c | 15 ++++++++++----- 3 files changed, 17 insertions(+), 11 deletions(-) diff --git a/exec.c b/exec.c index 4579b30e82..c5ce6c82b0 100644 --- a/exec.c +++ b/exec.c @@ -1894,10 +1894,10 @@ void *qemu_get_ram_ptr(RAMBlock *ram_block, ram_addr_t addr) * In that case just map until the end of the page. */ if (block->offset == 0) { - return xen_map_cache(addr, 0, 0); + return xen_map_cache(addr, 0, 0, false); } - block->host = xen_map_cache(block->offset, block->max_length, 1); + block->host = xen_map_cache(block->offset, block->max_length, 1, false); } return ramblock_ptr(block, addr - block->offset); } @@ -1928,10 +1928,10 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_block, ram_addr_t addr, * In that case just map the requested area. */ if (block->offset == 0) { - return xen_map_cache(addr, *size, 1); + return xen_map_cache(addr, *size, 1, true); } - block->host = xen_map_cache(block->offset, block->max_length, 1); + block->host = xen_map_cache(block->offset, block->max_length, 1, true); } return ramblock_ptr(block, offset_inside_block); diff --git a/include/sysemu/xen-mapcache.h b/include/sysemu/xen-mapcache.h index c849489fb2..42c456161a 100644 --- a/include/sysemu/xen-mapcache.h +++ b/include/sysemu/xen-mapcache.h @@ -18,7 +18,7 @@ typedef hwaddr (*phys_offset_to_gaddr_t)(hwaddr start_addr, void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque); uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size, - uint8_t lock); + uint8_t lock, bool dma); ram_addr_t xen_ram_addr_from_mapcache(void *ptr); void xen_invalidate_map_cache_entry(uint8_t *buffer); void xen_invalidate_map_cache(void); @@ -32,7 +32,8 @@ static inline void xen_map_cache_init(phys_offset_to_gaddr_t f, static inline uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size, - uint8_t lock) + uint8_t lock, + bool dma) { abort(); } diff --git a/xen-mapcache.c b/xen-mapcache.c index 49f394a777..279f09e4df 100644 --- a/xen-mapcache.c +++ b/xen-mapcache.c @@ -63,6 +63,7 @@ typedef struct MapCacheRev { hwaddr paddr_index; hwaddr size; QTAILQ_ENTRY(MapCacheRev) next; + bool dma; } MapCacheRev; typedef struct MapCache { @@ -201,7 +202,7 @@ static void xen_remap_bucket(MapCacheEntry *entry, } static uint8_t *xen_map_cache_unlocked(hwaddr phys_addr, hwaddr size, - uint8_t lock) + uint8_t lock, bool dma) { MapCacheEntry *entry, *pentry = NULL; hwaddr address_index; @@ -288,6 +289,7 @@ tryagain: if (lock) { MapCacheRev *reventry = g_malloc0(sizeof(MapCacheRev)); entry->lock++; + reventry->dma = dma; reventry->vaddr_req = mapcache->last_entry->vaddr_base + address_offset; reventry->paddr_index = mapcache->last_entry->paddr_index; reventry->size = entry->size; @@ -299,12 +301,12 @@ tryagain: } uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size, - uint8_t lock) + uint8_t lock, bool dma) { uint8_t *p; mapcache_lock(); - p = xen_map_cache_unlocked(phys_addr, size, lock); + p = xen_map_cache_unlocked(phys_addr, size, lock, dma); mapcache_unlock(); return p; } @@ -424,8 +426,11 @@ void xen_invalidate_map_cache(void) mapcache_lock(); QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) { - DPRINTF("There should be no locked mappings at this time, " - "but "TARGET_FMT_plx" -> %p is present\n", + if (!reventry->dma) { + continue; + } + fprintf(stderr, "Locked DMA mapping while invalidating mapcache!" + " "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req); }
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