[PATCH] nvme: implement support for nvme relaxed effects

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

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 we don't need to do that.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/nvme/host/core.c | 4 ++++
 include/linux/nvme.h     | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 975245527c1fc..75927e8579857 100644
--- 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 bc605ec4a3fd0..3ef4053ea9500 100644
--- 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),
-- 
2.34.1