816077299c
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. Upstream discussion: https://lists.nongnu.org/archive/html/qemu-devel/2023-08/msg04239.html Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
101 lines
4.3 KiB
Diff
101 lines
4.3 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Fiona Ebner <f.ebner@proxmox.com>
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Date: Thu, 24 Aug 2023 11:22:21 +0200
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Subject: [PATCH] hw/ide: reset: cancel async DMA operation before reseting
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state
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If there is a pending DMA operation during ide_bus_reset(), the fact
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that the IDEstate is already reset before the operation is canceled
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can be problematic. In particular, ide_dma_cb() might be called and
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then use the reset IDEstate which contains the signature after the
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reset. When used to construct the IO operation this leads to
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ide_get_sector() returning 0 and nsector being 1. This is particularly
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bad, because a write command will thus destroy the first sector which
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often contains a partition table or similar.
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Traces showing the unsolicited write happening with IDEstate
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0x5595af6949d0 being used after reset:
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> ahci_port_write ahci(0x5595af6923f0)[0]: port write [reg:PxSCTL] @ 0x2c: 0x00000300
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> ahci_reset_port ahci(0x5595af6923f0)[0]: reset port
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> ide_reset IDEstate 0x5595af6949d0
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> ide_reset IDEstate 0x5595af694da8
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> ide_bus_reset_aio aio_cancel
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> dma_aio_cancel dbs=0x7f64600089a0
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> dma_blk_cb dbs=0x7f64600089a0 ret=0
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> dma_complete dbs=0x7f64600089a0 ret=0 cb=0x5595acd40b30
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> ahci_populate_sglist ahci(0x5595af6923f0)[0]
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> ahci_dma_prepare_buf ahci(0x5595af6923f0)[0]: prepare buf limit=512 prepared=512
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> ide_dma_cb IDEState 0x5595af6949d0; sector_num=0 n=1 cmd=DMA WRITE
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> dma_blk_io dbs=0x7f6420802010 bs=0x5595ae2c6c30 offset=0 to_dev=1
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> dma_blk_cb dbs=0x7f6420802010 ret=0
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> (gdb) p *qiov
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> $11 = {iov = 0x7f647c76d840, niov = 1, {{nalloc = 1, local_iov = {iov_base = 0x0,
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> iov_len = 512}}, {__pad = "\001\000\000\000\000\000\000\000\000\000\000",
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> size = 512}}}
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> (gdb) bt
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> #0 blk_aio_pwritev (blk=0x5595ae2c6c30, offset=0, qiov=0x7f6420802070, flags=0,
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> cb=0x5595ace6f0b0 <dma_blk_cb>, opaque=0x7f6420802010)
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> at ../block/block-backend.c:1682
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> #1 0x00005595ace6f185 in dma_blk_cb (opaque=0x7f6420802010, ret=<optimized out>)
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> at ../softmmu/dma-helpers.c:179
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> #2 0x00005595ace6f778 in dma_blk_io (ctx=0x5595ae0609f0,
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> sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512,
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> io_func=io_func@entry=0x5595ace6ee30 <dma_blk_write_io_func>,
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> io_func_opaque=io_func_opaque@entry=0x5595ae2c6c30,
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> cb=0x5595acd40b30 <ide_dma_cb>, opaque=0x5595af6949d0,
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> dir=DMA_DIRECTION_TO_DEVICE) at ../softmmu/dma-helpers.c:244
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> #3 0x00005595ace6f90a in dma_blk_write (blk=0x5595ae2c6c30,
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> sg=sg@entry=0x5595af694d00, offset=offset@entry=0, align=align@entry=512,
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> cb=cb@entry=0x5595acd40b30 <ide_dma_cb>, opaque=opaque@entry=0x5595af6949d0)
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> at ../softmmu/dma-helpers.c:280
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> #4 0x00005595acd40e18 in ide_dma_cb (opaque=0x5595af6949d0, ret=<optimized out>)
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> at ../hw/ide/core.c:953
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> #5 0x00005595ace6f319 in dma_complete (ret=0, dbs=0x7f64600089a0)
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> at ../softmmu/dma-helpers.c:107
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> #6 dma_blk_cb (opaque=0x7f64600089a0, ret=0) at ../softmmu/dma-helpers.c:127
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> #7 0x00005595ad12227d in blk_aio_complete (acb=0x7f6460005b10)
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> at ../block/block-backend.c:1527
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> #8 blk_aio_complete (acb=0x7f6460005b10) at ../block/block-backend.c:1524
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> #9 blk_aio_write_entry (opaque=0x7f6460005b10) at ../block/block-backend.c:1594
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> #10 0x00005595ad258cfb in coroutine_trampoline (i0=<optimized out>,
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> i1=<optimized out>) at ../util/coroutine-ucontext.c:177
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Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
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---
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hw/ide/core.c | 14 +++++++-------
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1 file changed, 7 insertions(+), 7 deletions(-)
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diff --git a/hw/ide/core.c b/hw/ide/core.c
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index 08e1f0c3d7..148fccdef2 100644
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--- a/hw/ide/core.c
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+++ b/hw/ide/core.c
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@@ -2513,19 +2513,19 @@ static void ide_dummy_transfer_stop(IDEState *s)
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void ide_bus_reset(IDEBus *bus)
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{
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- bus->unit = 0;
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- bus->cmd = 0;
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- ide_reset(&bus->ifs[0]);
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- ide_reset(&bus->ifs[1]);
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- ide_clear_hob(bus);
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-
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- /* pending async DMA */
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+ /* pending async DMA - needs the IDEState before it is reset */
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if (bus->dma->aiocb) {
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trace_ide_bus_reset_aio();
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blk_aio_cancel(bus->dma->aiocb);
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bus->dma->aiocb = NULL;
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}
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+ bus->unit = 0;
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+ bus->cmd = 0;
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+ ide_reset(&bus->ifs[0]);
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+ ide_reset(&bus->ifs[1]);
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+ ide_clear_hob(bus);
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+
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/* reset dma provider too */
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if (bus->dma->ops->reset) {
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bus->dma->ops->reset(bus->dma);
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