On Thu, Oct 01, 2020 at 09:29:22AM -0600, Keith Busch wrote:
> On Thu, Oct 01, 2020 at 11:22:46AM +0000, Niklas Cassel wrote:
> > On Mon, Sep 28, 2020 at 11:35:19AM +0900, Dmitry Fomichev wrote:
> > > From: Niklas Cassel <niklas.cas...@wdc.com>
> > > @@ -2222,6 +2328,30 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr
> > > offset, uint64_t data,
> > > break;
> > > case 0x14: /* CC */
> > > trace_pci_nvme_mmio_cfg(data & 0xffffffff);
> > > +
> > > + if (NVME_CC_CSS(data) != NVME_CC_CSS(n->bar.cc)) {
> > > + if (NVME_CC_EN(n->bar.cc)) {
> >
> > I just saw this print when doing controller reset on a live system.
> >
> > Added a debug print:
> > nvme_write_bar WRITING: 0x0 previous: 0x464061
> >
> > so the second if-statement has to be:
> >
> > if (NVME_CC_EN(n->bar.cc) && NVME_CC_EN(data)) {
> >
> > Sorry for introducing the bug in the first place.
>
> No worries.
>
> I don't think the check should be here at all, really. The only check for
> valid
> CSS should be in nvme_start_ctrl(), which I posted yesterday.
The reasoning for this additional check is this:
From CC.CC register description:
"This field shall only be changed when the controller
is disabled (CC.EN is cleared to ‘0’)."
In the QEMU model, we have functions, e.g. nvme_cmd_effects(),
that uses n->bar.cc "at runtime".
So I don't think that simply checking for valid CSS in
nvme_start_ctrl() is sufficient.
Thoughts?
Kind regards,
Niklas
>
> > > + NVME_GUEST_ERR(pci_nvme_err_change_css_when_enabled,
> > > + "changing selected command set when
> > > enabled");
> > > + } else {
> > > + switch (NVME_CC_CSS(data)) {
> > > + case CSS_NVM_ONLY:
> > > + trace_pci_nvme_css_nvm_cset_selected_by_host(data &
> > > +
> > > 0xffffffff);
> > > + break;
> > > + case CSS_CSI:
> > > + NVME_SET_CC_CSS(n->bar.cc, CSS_CSI);
> > > + trace_pci_nvme_css_all_csets_sel_by_host(data &
> > > 0xffffffff);
> > > + break;
> > > + case CSS_ADMIN_ONLY:
> > > + break;
> > > + default:
> > > + NVME_GUEST_ERR(pci_nvme_ub_unknown_css_value,
> > > + "unknown value in CC.CSS field");
> > > + }
> > > + }
> > > + }
