On Jan 18 21:41, Minwoo Im wrote: > On 21-01-18 10:46:55, Klaus Jensen wrote: > > From: Klaus Jensen <k.jen...@samsung.com> > > > > 64 bit registers like ASQ and ACQ should be writable by both a hi/lo 32 > > bit write combination as well as a plain 64 bit write. The spec does not > > define ordering on the hi/lo split, but the code currently assumes that > > the low order bits are written first. Additionally, the code does not > > consider that another address might already have been written into the > > register, causing the OR'ing to result in a bad address. > > > > Fix this by explicitly overwriting only the low or high order bits for > > 32 bit writes. > > > > Signed-off-by: Klaus Jensen <k.jen...@samsung.com> > > --- > > hw/block/nvme.c | 10 ++++++---- > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/hw/block/nvme.c b/hw/block/nvme.c > > index bd7e258c3c26..40b9f8ccfc0e 100644 > > --- a/hw/block/nvme.c > > +++ b/hw/block/nvme.c > > @@ -3781,19 +3781,21 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr > > offset, uint64_t data, > > trace_pci_nvme_mmio_aqattr(data & 0xffffffff); > > break; > > case 0x28: /* ASQ */ > > - n->bar.asq = data; > > + n->bar.asq = size == 8 ? data : > > + (n->bar.asq & ~0xffffffff) | (data & 0xffffffff); > ^^^^^^^^^^^ > If this one is to unmask lower 32bits other than higher 32bits, then > it should be: > > (n->bar.asq & ~0xffffffffULL) >
Ouch. Yes, thanks!
> Also, maybe we should take care of lower than 4bytes as:
>
> .min_access_size = 2,
> .max_access_size = 8,
>
> Even we have some error messages up there with:
>
> if (unlikely(size < sizeof(uint32_t))) {
> NVME_GUEST_ERR(pci_nvme_ub_mmiowr_toosmall,
> "MMIO write smaller than 32-bits,"
> " offset=0x%"PRIx64", size=%u",
> offset, size);
> /* should be ignored, fall through for now */
> }
>
> It's a fall-thru error, and that's it. I would prefer not to have this
> error and support for 2bytes access also, OR do not support for 2bytes
> access for this MMIO area.
>
The spec requires aligned 32 bit accesses (or the size of the register),
so maybe it's about time we actually ignore instead of falling through.
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