Re: [PATCH v3 07/18] hw/block/nvme: add support for the get log page command

[Klaus Jensen <its@irrelevant.dk>]

On Jul 29 13:24, Maxim Levitsky wrote:
> On Mon, 2020-07-06 at 08:12 +0200, Klaus Jensen wrote:
> > From: Klaus Jensen <k.jensen@samsung.com>
> > 
> > Add support for the Get Log Page command and basic implementations of
> > the mandatory Error Information, SMART / Health Information and Firmware
> > Slot Information log pages.
> > 
> > In violation of the specification, the SMART / Health Information log
> > page does not persist information over the lifetime of the controller
> > because the device has no place to store such persistent state.
> > 
> > Note that the LPA field in the Identify Controller data structure
> > intentionally has bit 0 cleared because there is no namespace specific
> > information in the SMART / Health information log page.
> > 
> > Required for compliance with NVMe revision 1.3d. See NVM Express 1.3d,
> > Section 5.14 ("Get Log Page command").
> > 
> > Signed-off-by: Klaus Jensen <klaus.jensen@cnexlabs.com>
> > Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> > Acked-by: Keith Busch <kbusch@kernel.org>
> > ---
> >  hw/block/nvme.c       | 140 +++++++++++++++++++++++++++++++++++++++++-
> >  hw/block/nvme.h       |   2 +
> >  hw/block/trace-events |   2 +
> >  include/block/nvme.h  |   8 ++-
> >  4 files changed, 149 insertions(+), 3 deletions(-)
> > 
> > diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> > index b6bc75eb61a2..7cb3787638f6 100644
> > --- a/hw/block/nvme.c
> > +++ b/hw/block/nvme.c
> > @@ -606,6 +606,140 @@ static uint16_t nvme_create_sq(NvmeCtrl *n, NvmeCmd *cmd)
> >      return NVME_SUCCESS;
> >  }
> >  
> > +static uint16_t nvme_smart_info(NvmeCtrl *n, NvmeCmd *cmd, uint32_t buf_len,
> > +                                uint64_t off, NvmeRequest *req)
> > +{
> > +    uint64_t prp1 = le64_to_cpu(cmd->dptr.prp1);
> > +    uint64_t prp2 = le64_to_cpu(cmd->dptr.prp2);
> > +    uint32_t nsid = le32_to_cpu(cmd->nsid);
> > +
> > +    uint32_t trans_len;
> > +    time_t current_ms;
> > +    uint64_t units_read = 0, units_written = 0;
> > +    uint64_t read_commands = 0, write_commands = 0;
> > +    NvmeSmartLog smart;
> > +    BlockAcctStats *s;
> > +
> > +    if (nsid && nsid != 0xffffffff) {
> > +        return NVME_INVALID_FIELD | NVME_DNR;
> > +    }
> Correct.
> > +
> > +    s = blk_get_stats(n->conf.blk);
> > +
> > +    units_read = s->nr_bytes[BLOCK_ACCT_READ] >> BDRV_SECTOR_BITS;
> > +    units_written = s->nr_bytes[BLOCK_ACCT_WRITE] >> BDRV_SECTOR_BITS;
> > +    read_commands = s->nr_ops[BLOCK_ACCT_READ];
> > +    write_commands = s->nr_ops[BLOCK_ACCT_WRITE];
> > +
> > +    if (off > sizeof(smart)) {
> > +        return NVME_INVALID_FIELD | NVME_DNR;
> > +    }
> > +
> > +    trans_len = MIN(sizeof(smart) - off, buf_len);
> > +
> > +    memset(&smart, 0x0, sizeof(smart));
> > +
> > +    smart.data_units_read[0] = cpu_to_le64(units_read / 1000);
> > +    smart.data_units_written[0] = cpu_to_le64(units_written / 1000);
> Tiny nitpick - the spec asks the value to be rounded up
> 

Ouch. You are correct. I'll swap that for a DIV_ROUND_UP.

> > +static uint16_t nvme_get_log(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
> > +{
> > +    uint32_t dw10 = le32_to_cpu(cmd->cdw10);
> > +    uint32_t dw11 = le32_to_cpu(cmd->cdw11);
> > +    uint32_t dw12 = le32_to_cpu(cmd->cdw12);
> > +    uint32_t dw13 = le32_to_cpu(cmd->cdw13);
> > +    uint8_t  lid = dw10 & 0xff;
> > +    uint8_t  lsp = (dw10 >> 8) & 0xf;
> > +    uint8_t  rae = (dw10 >> 15) & 0x1;
> > +    uint32_t numdl, numdu;
> > +    uint64_t off, lpol, lpou;
> > +    size_t   len;
> > +
> Nitpick: don't we want to check NSID=0 || NSID=0xFFFFFFFF here too?
> 

The spec lists Get Log Page with "Yes" under "Namespace Identifier Used"
but no log pages in v1.3 or v1.4 are namespace specific so we expect
NSID to always be 0 or 0xffffffff. But, there are TPs that have
namespace specific log pages (i.e. TP 4053 Zoned Namepaces). So, it is
not invalid to have NSID set to something.

So, I think we have to defer handling of NSID values to the individual
log pages (like we do for the SMART page).