From e85fa0f42359527628b5b2243c514acc9670871a Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 8 Mar 2018 15:58:16 +0100 Subject: [PATCH 03/17] address_space_read: address_space_to_flatview needs RCU lock RH-Author: Paolo Bonzini Message-id: <20180308155819.20598-4-pbonzini@redhat.com> Patchwork-id: 79190 O-Subject: [RHEL7.5 qemu-kvm-rhev PATCH 3/6] address_space_read: address_space_to_flatview needs RCU lock Bugzilla: 1554930 RH-Acked-by: Cornelia Huck RH-Acked-by: Thomas Huth RH-Acked-by: Laurent Vivier address_space_read is calling address_space_to_flatview but it can be called outside the RCU lock. To fix it, push the rcu_read_lock/unlock pair up from flatview_read_full to address_space_read's constant size fast path and address_space_read_full. Reviewed-by: Alexey Kardashevskiy Signed-off-by: Paolo Bonzini (cherry pick from commit b2a44fcad74f1cc7a6786d38eba7db12ab2352ba) Signed-off-by: Miroslav Rezanina --- exec.c | 38 +++++++++++++++++++++++++------------- include/exec/memory.h | 23 +++++++++-------------- 2 files changed, 34 insertions(+), 27 deletions(-) diff --git a/exec.c b/exec.c index 8b50133..43c66da 100644 --- a/exec.c +++ b/exec.c @@ -2512,6 +2512,8 @@ static const MemoryRegionOps watch_mem_ops = { .endianness = DEVICE_NATIVE_ENDIAN, }; +static MemTxResult flatview_read(FlatView *fv, hwaddr addr, + MemTxAttrs attrs, uint8_t *buf, int len); static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs, const uint8_t *buf, int len); static bool flatview_access_valid(FlatView *fv, hwaddr addr, int len, @@ -3029,24 +3031,18 @@ MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr, return result; } -MemTxResult flatview_read_full(FlatView *fv, hwaddr addr, - MemTxAttrs attrs, uint8_t *buf, int len) +/* Called from RCU critical section. */ +static MemTxResult flatview_read(FlatView *fv, hwaddr addr, + MemTxAttrs attrs, uint8_t *buf, int len) { hwaddr l; hwaddr addr1; MemoryRegion *mr; - MemTxResult result = MEMTX_OK; - - if (len > 0) { - rcu_read_lock(); - l = len; - mr = flatview_translate(fv, addr, &addr1, &l, false); - result = flatview_read_continue(fv, addr, attrs, buf, len, - addr1, l, mr); - rcu_read_unlock(); - } - return result; + l = len; + mr = flatview_translate(fv, addr, &addr1, &l, false); + return flatview_read_continue(fv, addr, attrs, buf, len, + addr1, l, mr); } static MemTxResult flatview_rw(FlatView *fv, hwaddr addr, MemTxAttrs attrs, @@ -3067,6 +3063,22 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr addr, addr, attrs, buf, len, is_write); } +MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr, + MemTxAttrs attrs, uint8_t *buf, int len) +{ + MemTxResult result = MEMTX_OK; + FlatView *fv; + + if (len > 0) { + rcu_read_lock(); + fv = address_space_to_flatview(as); + result = flatview_read(fv, addr, attrs, buf, len); + rcu_read_unlock(); + } + + return result; +} + MemTxResult address_space_write(AddressSpace *as, hwaddr addr, MemTxAttrs attrs, const uint8_t *buf, int len) diff --git a/include/exec/memory.h b/include/exec/memory.h index 3df0dcc..a66b6ef 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -1917,13 +1917,12 @@ void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len, /* Internal functions, part of the implementation of address_space_read. */ +MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr, + MemTxAttrs attrs, uint8_t *buf, int len); MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr, MemTxAttrs attrs, uint8_t *buf, int len, hwaddr addr1, hwaddr l, MemoryRegion *mr); - -MemTxResult flatview_read_full(FlatView *fv, hwaddr addr, - MemTxAttrs attrs, uint8_t *buf, int len); void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr); static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write) @@ -1942,7 +1941,7 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write) * * Return a MemTxResult indicating whether the operation succeeded * or failed (eg unassigned memory, device rejected the transaction, - * IOMMU fault). + * IOMMU fault). Called within RCU critical section. * * @as: #AddressSpace to be accessed * @addr: address within that address space @@ -1950,17 +1949,20 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write) * @buf: buffer with the data transferred */ static inline __attribute__((__always_inline__)) -MemTxResult flatview_read(FlatView *fv, hwaddr addr, MemTxAttrs attrs, - uint8_t *buf, int len) +MemTxResult address_space_read(AddressSpace *as, hwaddr addr, + MemTxAttrs attrs, uint8_t *buf, + int len) { MemTxResult result = MEMTX_OK; hwaddr l, addr1; void *ptr; MemoryRegion *mr; + FlatView *fv; if (__builtin_constant_p(len)) { if (len) { rcu_read_lock(); + fv = address_space_to_flatview(as); l = len; mr = flatview_translate(fv, addr, &addr1, &l, false); if (len == l && memory_access_is_direct(mr, false)) { @@ -1973,18 +1975,11 @@ MemTxResult flatview_read(FlatView *fv, hwaddr addr, MemTxAttrs attrs, rcu_read_unlock(); } } else { - result = flatview_read_full(fv, addr, attrs, buf, len); + result = address_space_read_full(as, addr, attrs, buf, len); } return result; } -static inline MemTxResult address_space_read(AddressSpace *as, hwaddr addr, - MemTxAttrs attrs, uint8_t *buf, - int len) -{ - return flatview_read(address_space_to_flatview(as), addr, attrs, buf, len); -} - /** * address_space_read_cached: read from a cached RAM region * -- 1.8.3.1