nvme: implement support for relaxed effects

NVM Express TP4167 provides a way for controllers to report a relaxed
execution constraint. Specifically, it notifies of exclusivity for IO
vs. admin commands instead of grouping these together. If set, then we
don't need to freeze IO in order to execute that admin command. The
freezing distrupts IO processes, so it's nice to avoid that if the
controller tells us it's not necessary.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 60537c9224bf9341de0c01449f47e05032020e43..0a96362912ceda0a035b916f432b24afb261f6a7 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1153,6 +1153,10 @@ u32 nvme_command_effects(struct nvme_ctrl *ctrl, struct nvme_ns *ns, u8 opcode)
                effects &= ~NVME_CMD_EFFECTS_CSE_MASK;
        } else {
                effects = le32_to_cpu(ctrl->effects->acs[opcode]);
+
+               /* Ignore execution restrictions if any relaxation bits are set */
+               if (effects & NVME_CMD_EFFECTS_CSER_MASK)
+                       effects &= ~NVME_CMD_EFFECTS_CSE_MASK;
        }
 
        return effects;

diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index bc605ec4a3fd06f9145242827fe310a760f00122..3ef4053ea9500bc975acd5433ff387633c92eb62 100644 (file)
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -646,6 +646,7 @@ enum {
        NVME_CMD_EFFECTS_NCC            = 1 << 2,
        NVME_CMD_EFFECTS_NIC            = 1 << 3,
        NVME_CMD_EFFECTS_CCC            = 1 << 4,
+       NVME_CMD_EFFECTS_CSER_MASK      = GENMASK(15, 14),
        NVME_CMD_EFFECTS_CSE_MASK       = GENMASK(18, 16),
        NVME_CMD_EFFECTS_UUID_SEL       = 1 << 19,
        NVME_CMD_EFFECTS_SCOPE_MASK     = GENMASK(31, 20),