Commit 1551ed5a authored by Jens Axboe's avatar Jens Axboe
Browse files

Merge tag 'nvme-6.2-2022-12-29' of git://git.infradead.org/nvme into block-6.2 

Pull NVMe fixes from Christoph:

"nvme fixes for Linux 6.2

 - fix various problems in handling the Command Supported and Effects log
   (Christoph Hellwig)
 - don't allow unprivileged passthrough of commands that don't transfer
   data but modify logical block content (Christoph Hellwig)
 - add a features and quirks policy document (Christoph Hellwig)
 - fix some really nasty code that was correct but made smatch complain
   (Sagi Grimberg)"

* tag 'nvme-6.2-2022-12-29' of git://git.infradead.org/nvme:
  nvme-auth: fix smatch warning complaints
  nvme: consult the CSE log page for unprivileged passthrough
  nvme: also return I/O command effects from nvme_command_effects
  nvmet: don't defer passthrough commands with trivial effects to the workqueue
  nvmet: set the LBCC bit for commands that modify data
  nvmet: use NVME_CMD_EFFECTS_CSUPP instead of open coding it
  nvme: fix the NVME_CMD_EFFECTS_CSE_MASK definition
  docs, nvme: add a feature and quirk policy document
parents 88d356ca 76807fcd

Documentation/maintainer/maintainer-entry-profile.rst

+1 −0
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@@ -104,3 +104,4 @@ to do something different in the near future. 
   ../riscv/patch-acceptance

   ../driver-api/media/maintainer-entry-profile

   ../driver-api/vfio-pci-device-specific-driver-acceptance

   ../nvme/feature-and-quirk-policy

Documentation/nvme/feature-and-quirk-policy.rst

0 → 100644
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.. SPDX-License-Identifier: GPL-2.0



=======================================

Linux NVMe feature and and quirk policy

=======================================



This file explains the policy used to decide what is supported by the

Linux NVMe driver and what is not.





Introduction

============



NVM Express is an open collection of standards and information.



The Linux NVMe host driver in drivers/nvme/host/ supports devices

implementing the NVM Express (NVMe) family of specifications, which

currently consists of a number of documents:



 - the NVMe Base specification

 - various Command Set specifications (e.g. NVM Command Set)

 - various Transport specifications (e.g. PCIe, Fibre Channel, RDMA, TCP)

 - the NVMe Management Interface specification



See https://nvmexpress.org/developers/ for the NVMe specifications.





Supported features

==================



NVMe is a large suite of specifications, and contains features that are only

useful or suitable for specific use-cases. It is important to note that Linux

does not aim to implement every feature in the specification.  Every additional

feature implemented introduces more code, more maintenance and potentially more

bugs.  Hence there is an inherent tradeoff between functionality and

maintainability of the NVMe host driver.



Any feature implemented in the Linux NVMe host driver must support the

following requirements:



  1. The feature is specified in a release version of an official NVMe

     specification, or in a ratified Technical Proposal (TP) that is

     available on NVMe website. Or if it is not directly related to the

     on-wire protocol, does not contradict any of the NVMe specifications.

  2. Does not conflict with the Linux architecture, nor the design of the

     NVMe host driver.

  3. Has a clear, indisputable value-proposition and a wide consensus across

     the community.



Vendor specific extensions are generally not supported in the NVMe host

driver.



It is strongly recommended to work with the Linux NVMe and block layer

maintainers and get feedback on specification changes that are intended

to be used by the Linux NVMe host driver in order to avoid conflict at a

later stage.





Quirks

======



Sometimes implementations of open standards fail to correctly implement parts

of the standards.  Linux uses identifier-based quirks to work around such

implementation bugs.  The intent of quirks is to deal with widely available

hardware, usually consumer, which Linux users can't use without these quirks.

Typically these implementations are not or only superficially tested with Linux

by the hardware manufacturer.



The Linux NVMe maintainers decide ad hoc whether to quirk implementations

based on the impact of the problem to Linux users and how it impacts

maintainability of the driver.  In general quirks are a last resort, if no

firmware updates or other workarounds are available from the vendor.



Quirks will not be added to the Linux kernel for hardware that isn't available

on the mass market.  Hardware that fails qualification for enterprise Linux

distributions, ChromeOS, Android or other consumers of the Linux kernel

should be fixed before it is shipped instead of relying on Linux quirks.

MAINTAINERS

+1 −0
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@@ -14827,6 +14827,7 @@ L: linux-nvme@lists.infradead.org 
S:	Supported

W:	http://git.infradead.org/nvme.git

T:	git://git.infradead.org/nvme.git

F:	Documentation/nvme/

F:	drivers/nvme/host/

F:	drivers/nvme/common/

F:	include/linux/nvme*

drivers/nvme/host/auth.c

+1 −1
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@@ -953,7 +953,7 @@ int nvme_auth_init_ctrl(struct nvme_ctrl *ctrl) 
		goto err_free_dhchap_secret;



	if (!ctrl->opts->dhchap_secret && !ctrl->opts->dhchap_ctrl_secret)

		return ret;

		return 0;



	ctrl->dhchap_ctxs = kvcalloc(ctrl_max_dhchaps(ctrl),

				sizeof(*chap), GFP_KERNEL);

drivers/nvme/host/core.c

+26 −6
Original line number Diff line number Diff line
@@ -1074,6 +1074,18 @@ static u32 nvme_known_admin_effects(u8 opcode) 
	return 0;

}



static u32 nvme_known_nvm_effects(u8 opcode)

{

	switch (opcode) {

	case nvme_cmd_write:

	case nvme_cmd_write_zeroes:

	case nvme_cmd_write_uncor:

		 return NVME_CMD_EFFECTS_LBCC;

	default:

		return 0;

	}

}



u32 nvme_command_effects(struct nvme_ctrl *ctrl, struct nvme_ns *ns, u8 opcode)

{

	u32 effects = 0;
@@ -1081,16 +1093,24 @@ u32 nvme_command_effects(struct nvme_ctrl *ctrl, struct nvme_ns *ns, u8 opcode) 
	if (ns) {

		if (ns->head->effects)

			effects = le32_to_cpu(ns->head->effects->iocs[opcode]);

		if (ns->head->ids.csi == NVME_CAP_CSS_NVM)

			effects |= nvme_known_nvm_effects(opcode);

		if (effects & ~(NVME_CMD_EFFECTS_CSUPP | NVME_CMD_EFFECTS_LBCC))

			dev_warn_once(ctrl->device,

				"IO command:%02x has unhandled effects:%08x\n",

				"IO command:%02x has unusual effects:%08x\n",

				opcode, effects);

		return 0;

	}



		/*

		 * NVME_CMD_EFFECTS_CSE_MASK causes a freeze all I/O queues,

		 * which would deadlock when done on an I/O command.  Note that

		 * We already warn about an unusual effect above.

		 */

		effects &= ~NVME_CMD_EFFECTS_CSE_MASK;

	} else {

		if (ctrl->effects)

			effects = le32_to_cpu(ctrl->effects->acs[opcode]);

		effects |= nvme_known_admin_effects(opcode);

	}



	return effects;

}