On Mon, Mar 30, 2020 at 01:52:28PM +0100, Peter Maydell wrote: > In dcr_write_pcie() we take the iothread lock around a call to > pcie_host_mmcfg_udpate(). This is an incorrect attempt to deal with > the bug fixed in commit 235352ee6e73d7716, where we were not taking > the iothread lock before calling device dcr read/write functions. > (It's not sufficient locking, because although the other cases in the > switch statement won't assert, there is no locking which prevents > multiple guest CPUs from trying to access the PPC460EXPCIEState > struct at the same time and corrupting data.) > > Unfortunately with commit 235352ee6e73d7716 we are now trying > to recursively take the iothread lock, which will assert: > > $ qemu-system-ppc -M sam460ex --display none > ** > > ERROR:/home/petmay01/linaro/qemu-from-laptop/qemu/cpus.c:1830:qemu_mutex_lock_iothread_impl: > assertion failed: (!qemu_mutex_iothread_locked()) > Aborted (core dumped) > > Remove the locking within dcr_write_pcie(). > > Fixes: 235352ee6e73d7716 > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> > --- > I did a grep of hw/ppc and didn't see anything else that was doing > its own locking inside a dcr read/write fn. > ---
Applied to ppc-for-5.0, thanks. > hw/ppc/ppc440_uc.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/hw/ppc/ppc440_uc.c b/hw/ppc/ppc440_uc.c > index d5ea962249f..b30e093cbb0 100644 > --- a/hw/ppc/ppc440_uc.c > +++ b/hw/ppc/ppc440_uc.c > @@ -13,7 +13,6 @@ > #include "qemu/error-report.h" > #include "qapi/error.h" > #include "qemu/log.h" > -#include "qemu/main-loop.h" > #include "qemu/module.h" > #include "cpu.h" > #include "hw/irq.h" > @@ -1183,9 +1182,7 @@ static void dcr_write_pcie(void *opaque, int dcrn, > uint32_t val) > case PEGPL_CFGMSK: > s->cfg_mask = val; > size = ~(val & 0xfffffffe) + 1; > - qemu_mutex_lock_iothread(); > pcie_host_mmcfg_update(PCIE_HOST_BRIDGE(s), val & 1, s->cfg_base, > size); > - qemu_mutex_unlock_iothread(); > break; > case PEGPL_MSGBAH: > s->msg_base = ((uint64_t)val << 32) | (s->msg_base & 0xffffffff); -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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