From: Fiona Ebner <f.eb...@proxmox.com> If there is a pending DMA operation during ide_bus_reset(), the fact that the IDEState is already reset before the operation is canceled can be problematic. In particular, ide_dma_cb() might be called and then use the reset IDEState which contains the signature after the reset. When used to construct the IO operation this leads to ide_get_sector() returning 0 and nsector being 1. This is particularly bad, because a write command will thus destroy the first sector which often contains a partition table or similar.
Traces showing the unsolicited write happening with IDEState 0x5595af6949d0 being used after reset: > ahci_port_write ahci(0x5595af6923f0)[0]: port write [reg:PxSCTL] @ 0x2c: > 0x00000300 > ahci_reset_port ahci(0x5595af6923f0)[0]: reset port > ide_reset IDEstate 0x5595af6949d0 > ide_reset IDEstate 0x5595af694da8 > ide_bus_reset_aio aio_cancel > dma_aio_cancel dbs=0x7f64600089a0 > dma_blk_cb dbs=0x7f64600089a0 ret=0 > dma_complete dbs=0x7f64600089a0 ret=0 cb=0x5595acd40b30 > ahci_populate_sglist ahci(0x5595af6923f0)[0] > ahci_dma_prepare_buf ahci(0x5595af6923f0)[0]: prepare buf limit=512 > prepared=512 > ide_dma_cb IDEState 0x5595af6949d0; sector_num=0 n=1 cmd=DMA WRITE > dma_blk_io dbs=0x7f6420802010 bs=0x5595ae2c6c30 offset=0 to_dev=1 > dma_blk_cb dbs=0x7f6420802010 ret=0 > (gdb) p *qiov > $11 = {iov = 0x7f647c76d840, niov = 1, {{nalloc = 1, local_iov = {iov_base = > 0x0, > iov_len = 512}}, {__pad = > "\001\000\000\000\000\000\000\000\000\000\000", > size = 512}}} > (gdb) bt > #0 blk_aio_pwritev (blk=0x5595ae2c6c30, offset=0, qiov=0x7f6420802070, > flags=0, > cb=0x5595ace6f0b0 <dma_blk_cb>, opaque=0x7f6420802010) > at ../block/block-backend.c:1682 > #1 0x00005595ace6f185 in dma_blk_cb (opaque=0x7f6420802010, ret=<optimized > out>) > at ../softmmu/dma-helpers.c:179 > #2 0x00005595ace6f778 in dma_blk_io (ctx=0x5595ae0609f0, > sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512, > io_func=io_func@entry=0x5595ace6ee30 <dma_blk_write_io_func>, > io_func_opaque=io_func_opaque@entry=0x5595ae2c6c30, > cb=0x5595acd40b30 <ide_dma_cb>, opaque=0x5595af6949d0, > dir=DMA_DIRECTION_TO_DEVICE) at ../softmmu/dma-helpers.c:244 > #3 0x00005595ace6f90a in dma_blk_write (blk=0x5595ae2c6c30, > sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512, > cb=cb@entry=0x5595acd40b30 <ide_dma_cb>, > opaque=opaque@entry=0x5595af6949d0) > at ../softmmu/dma-helpers.c:280 > #4 0x00005595acd40e18 in ide_dma_cb (opaque=0x5595af6949d0, ret=<optimized > out>) > at ../hw/ide/core.c:953 > #5 0x00005595ace6f319 in dma_complete (ret=0, dbs=0x7f64600089a0) > at ../softmmu/dma-helpers.c:107 > #6 dma_blk_cb (opaque=0x7f64600089a0, ret=0) at ../softmmu/dma-helpers.c:127 > #7 0x00005595ad12227d in blk_aio_complete (acb=0x7f6460005b10) > at ../block/block-backend.c:1527 > #8 blk_aio_complete (acb=0x7f6460005b10) at ../block/block-backend.c:1524 > #9 blk_aio_write_entry (opaque=0x7f6460005b10) at > ../block/block-backend.c:1594 > #10 0x00005595ad258cfb in coroutine_trampoline (i0=<optimized out>, > i1=<optimized out>) at ../util/coroutine-ucontext.c:177 Signed-off-by: Fiona Ebner <f.eb...@proxmox.com> Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org> Tested-by: simon.r...@nutanix.com Message-ID: <20230906130922.142845-1-f.eb...@proxmox.com> Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org> --- hw/ide/core.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/hw/ide/core.c b/hw/ide/core.c index b5e0dcd29b..63ba665f3d 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -2515,19 +2515,19 @@ static void ide_dummy_transfer_stop(IDEState *s) void ide_bus_reset(IDEBus *bus) { - bus->unit = 0; - bus->cmd = 0; - ide_reset(&bus->ifs[0]); - ide_reset(&bus->ifs[1]); - ide_clear_hob(bus); - - /* pending async DMA */ + /* pending async DMA - needs the IDEState before it is reset */ if (bus->dma->aiocb) { trace_ide_bus_reset_aio(); blk_aio_cancel(bus->dma->aiocb); bus->dma->aiocb = NULL; } + bus->unit = 0; + bus->cmd = 0; + ide_reset(&bus->ifs[0]); + ide_reset(&bus->ifs[1]); + ide_clear_hob(bus); + /* reset dma provider too */ if (bus->dma->ops->reset) { bus->dma->ops->reset(bus->dma); -- 2.41.0