target/i386/tcg: Enable page walking from MMIO memory
commit9dab7bbb017d11b64c52239fa4e2f910a6a004f2
authorGregory Price <gregory.price@memverge.com>
Thu, 7 Mar 2024 15:53:04 +0000 (7 15:53 +0000)
committerPhilippe Mathieu-Daudé <philmd@linaro.org>
Tue, 26 Mar 2024 13:23:50 +0000 (26 14:23 +0100)
treed6bf10ef4af71eae229415613edf9376d70e651c
parent096ae430a7b5a704af4cd94dca7200d6cb069991
target/i386/tcg: Enable page walking from MMIO memory

CXL emulation of interleave requires read and write hooks due to
requirement for subpage granularity. The Linux kernel stack now enables
using this memory as conventional memory in a separate NUMA node. If a
process is deliberately forced to run from that node
$ numactl --membind=1 ls
the page table walk on i386 fails.

Useful part of backtrace:

    (cpu=cpu@entry=0x555556fd9000, fmt=fmt@entry=0x555555fe3378 "cpu_io_recompile: could not find TB for pc=%p")
    at ../../cpu-target.c:359
    (retaddr=0, addr=19595792376, attrs=..., xlat=<optimized out>, cpu=0x555556fd9000, out_offset=<synthetic pointer>)
    at ../../accel/tcg/cputlb.c:1339
    (cpu=0x555556fd9000, full=0x7fffee0d96e0, ret_be=ret_be@entry=0, addr=19595792376, size=size@entry=8, mmu_idx=4, type=MMU_DATA_LOAD, ra=0) at ../../accel/tcg/cputlb.c:2030
    (cpu=cpu@entry=0x555556fd9000, p=p@entry=0x7ffff56fddc0, mmu_idx=<optimized out>, type=type@entry=MMU_DATA_LOAD, memop=<optimized out>, ra=ra@entry=0) at ../../accel/tcg/cputlb.c:2356
    (cpu=cpu@entry=0x555556fd9000, addr=addr@entry=19595792376, oi=oi@entry=52, ra=ra@entry=0, access_type=access_type@entry=MMU_DATA_LOAD) at ../../accel/tcg/cputlb.c:2439
    at ../../accel/tcg/ldst_common.c.inc:301
    at ../../target/i386/tcg/sysemu/excp_helper.c:173
    (err=0x7ffff56fdf80, out=0x7ffff56fdf70, mmu_idx=0, access_type=MMU_INST_FETCH, addr=18446744072116178925, env=0x555556fdb7c0)
    at ../../target/i386/tcg/sysemu/excp_helper.c:578
    (cs=0x555556fd9000, addr=18446744072116178925, size=<optimized out>, access_type=MMU_INST_FETCH, mmu_idx=0, probe=<optimized out>, retaddr=0) at ../../target/i386/tcg/sysemu/excp_helper.c:604

Avoid this by plumbing the address all the way down from
x86_cpu_tlb_fill() where is available as retaddr to the actual accessors
which provide it to probe_access_full() which already handles MMIO accesses.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2180
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2220
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Gregory Price <gregory.price@memverge.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-ID: <20240307155304.31241-2-Jonathan.Cameron@huawei.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
target/i386/tcg/sysemu/excp_helper.c