[PATCH v8 0/4] Add parameter for disabling ACS redirection for P2P

[PATCH v8 0/4] Add parameter for disabling ACS redirection for P2P

[Logan Gunthorpe]

Changes since v6:
* Fixed order of operations for device specific disable function as
  noticed by Alex
* Rebased onto v4.18-rc5 (no conflicts)

Changes since v5:
* Add a quirk to handle the Intel SPT PCH case (as pointed out by Alex)
* Warn in the case that we try to disable ACS redirect on a device
  that doesn't have the ACS capability (also suggested by Alex)
* Collect reviewed-by tag from Alex
* Rebased onto v4.18-rc4 (no conflicts)

Changes since v4:
* Fixed a couple documentation mistakes spotted by Randy

Changes since v3:
* Removed some of the cruft that was copied from the resource_alignment
  paramater (per Alex)
* A number of docuemntation fixes as noticed by Alex and Willy

Changes since v2:
* Rebased onto v4.18-rc1 (no conflicts)
* Minor tweaks to the documentation per Andy
* Removed the "path:" prefix and use the path parsing code
  for simple devices (as it works the same). Per a suggestion from Alex

Changes since v1:
* Reworked pci_dev_str_match_path using strrchr as suggested by Alex
* Collected Christian's Acks


Logan Gunthorpe (4):
  PCI: Make specifying PCI devices in kernel parameters reusable
  PCI: Allow specifying devices using a base bus and path of devfns
  PCI: Introduce disable_acs_redir quirk
  PCI: Introduce the disable_acs_redir parameter

 Documentation/admin-guide/kernel-parameters.txt |  41 +++-
 drivers/pci/pci.c                               | 310 +++++++++++++++++++-----
 drivers/pci/quirks.c                            |  78 +++++-
 include/linux/pci.h                             |   5 +
 4 files changed, 361 insertions(+), 73 deletions(-)

--
2.11.0

[PATCH v8 1/4] PCI: Make specifying PCI devices in kernel parameters reusable

[Logan Gunthorpe]

Separate out the code to match a PCI device with a string (typically
originating from a kernel parameter) from the
pci_specified_resource_alignment() function into its own helper
function.

While we are at it, this change fixes the kernel style of the function
(fixing a number of long lines and extra parentheses).

Additionally, make the analogous change to the kernel parameter
documentation: Separating the description of how to specify a PCI device
into it's own section at the head of the pci= parameter.

This patch should have no functional alterations.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Stephen Bates <sbates@raithlin.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  28 ++++-
 drivers/pci/pci.c                               | 157 ++++++++++++++++--------
 2 files changed, 126 insertions(+), 59 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 533ff5c68970..5cc215870ee1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2994,7 +2994,26 @@
 			See header of drivers/block/paride/pcd.c.
 			See also Documentation/blockdev/paride.txt.
 
-	pci=option[,option...]	[PCI] various PCI subsystem options:
+	pci=option[,option...]	[PCI] various PCI subsystem options.
+
+				Some options herein operate on a specific device
+				or a set of devices (<pci_dev>). These are
+				specified in one of the following formats:
+
+				[<domain>:]<bus>:<slot>.<func>
+				pci:<vendor>:<device>[:<subvendor>:<subdevice>]
+
+				Note: the first format specifies a PCI
+				bus/slot/function address which may change
+				if new hardware is inserted, if motherboard
+				firmware changes, or due to changes caused
+				by other kernel parameters. If the
+				domain is left unspecified, it is
+				taken to be zero. The second format
+				selects devices using IDs from the
+				configuration space which may match multiple
+				devices in the system.
+
 		earlydump	[X86] dump PCI config space before the kernel
 				changes anything
 		off		[X86] don't probe for the PCI bus
@@ -3123,11 +3142,10 @@
 				window. The default value is 64 megabytes.
 		resource_alignment=
 				Format:
-				[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
-				[<order of align>@]pci:<vendor>:<device>\
-						[:<subvendor>:<subdevice>][; ...]
+				[<order of align>@]<pci_dev>[; ...]
 				Specifies alignment and device to reassign
-				aligned memory resources.
+				aligned memory resources. How to
+				specify the device is described above.
 				If <order of align> is not specified,
 				PAGE_SIZE is used as alignment.
 				PCI-PCI bridge can be specified, if resource
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 316496e99da9..a6e5d195cbac 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -191,6 +191,92 @@ void __iomem *pci_ioremap_wc_bar(struct pci_dev *pdev, int bar)
 EXPORT_SYMBOL_GPL(pci_ioremap_wc_bar);
 #endif
 
+/**
+ * pci_dev_str_match - test if a string matches a device
+ * @dev:    the PCI device to test
+ * @p:      string to match the device against
+ * @endptr: pointer to the string after the match
+ *
+ * Test if a string (typically from a kernel parameter) matches a specified
+ * PCI device. The string may be of one of the following formats:
+ *
+ *   [<domain>:]<bus>:<slot>.<func>
+ *   pci:<vendor>:<device>[:<subvendor>:<subdevice>]
+ *
+ * The first format specifies a PCI bus/slot/function address which
+ * may change if new hardware is inserted, if motherboard firmware changes,
+ * or due to changes caused in kernel parameters. If the domain is
+ * left unspecified, it is taken to be 0.
+ *
+ * The second format matches devices using IDs in the configuration
+ * space which may match multiple devices in the system. A value of 0
+ * for any field will match all devices. (Note: this differs from
+ * in-kernel code that uses PCI_ANY_ID which is ~0; this is for
+ * legacy reasons and convenience so users don't have to specify
+ * FFFFFFFFs on the command line.)
+ *
+ * Returns 1 if the string matches the device, 0 if it does not and
+ * a negative error code if the string cannot be parsed.
+ */
+static int pci_dev_str_match(struct pci_dev *dev, const char *p,
+			     const char **endptr)
+{
+	int ret;
+	int seg, bus, slot, func, count;
+	unsigned short vendor, device, subsystem_vendor, subsystem_device;
+
+	if (strncmp(p, "pci:", 4) == 0) {
+		/* PCI vendor/device (subvendor/subdevice) ids are specified */
+		p += 4;
+		ret = sscanf(p, "%hx:%hx:%hx:%hx%n", &vendor, &device,
+			     &subsystem_vendor, &subsystem_device, &count);
+		if (ret != 4) {
+			ret = sscanf(p, "%hx:%hx%n", &vendor, &device, &count);
+			if (ret != 2)
+				return -EINVAL;
+
+			subsystem_vendor = 0;
+			subsystem_device = 0;
+		}
+
+		p += count;
+
+		if ((!vendor || vendor == dev->vendor) &&
+		    (!device || device == dev->device) &&
+		    (!subsystem_vendor ||
+			    subsystem_vendor == dev->subsystem_vendor) &&
+		    (!subsystem_device ||
+			    subsystem_device == dev->subsystem_device))
+			goto found;
+
+	} else {
+		/* PCI Bus,Slot,Function ids are specified */
+		ret = sscanf(p, "%x:%x:%x.%x%n", &seg, &bus, &slot,
+			     &func, &count);
+		if (ret != 4) {
+			seg = 0;
+			ret = sscanf(p, "%x:%x.%x%n", &bus, &slot,
+				     &func, &count);
+			if (ret != 3)
+				return -EINVAL;
+		}
+
+		p += count;
+
+		if (seg == pci_domain_nr(dev->bus) &&
+		    bus == dev->bus->number &&
+		    slot == PCI_SLOT(dev->devfn) &&
+		    func == PCI_FUNC(dev->devfn))
+			goto found;
+	}
+
+	*endptr = p;
+	return 0;
+
+found:
+	*endptr = p;
+	return 1;
+}
 
 static int __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn,
 				   u8 pos, int cap, int *ttl)
@@ -5492,10 +5578,10 @@ static DEFINE_SPINLOCK(resource_alignment_lock);
 static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
 							bool *resize)
 {
-	int seg, bus, slot, func, align_order, count;
-	unsigned short vendor, device, subsystem_vendor, subsystem_device;
+	int align_order, count;
 	resource_size_t align = pcibios_default_alignment();
-	char *p;
+	const char *p;
+	int ret;
 
 	spin_lock(&resource_alignment_lock);
 	p = resource_alignment_param;
@@ -5515,58 +5601,21 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
 		} else {
 			align_order = -1;
 		}
-		if (strncmp(p, "pci:", 4) == 0) {
-			/* PCI vendor/device (subvendor/subdevice) ids are specified */
-			p += 4;
-			if (sscanf(p, "%hx:%hx:%hx:%hx%n",
-				&vendor, &device, &subsystem_vendor, &subsystem_device, &count) != 4) {
-				if (sscanf(p, "%hx:%hx%n", &vendor, &device, &count) != 2) {
-					printk(KERN_ERR "PCI: Can't parse resource_alignment parameter: pci:%s\n",
-						p);
-					break;
-				}
-				subsystem_vendor = subsystem_device = 0;
-			}
-			p += count;
-			if ((!vendor || (vendor == dev->vendor)) &&
-				(!device || (device == dev->device)) &&
-				(!subsystem_vendor || (subsystem_vendor == dev->subsystem_vendor)) &&
-				(!subsystem_device || (subsystem_device == dev->subsystem_device))) {
-				*resize = true;
-				if (align_order == -1)
-					align = PAGE_SIZE;
-				else
-					align = 1 << align_order;
-				/* Found */
-				break;
-			}
-		}
-		else {
-			if (sscanf(p, "%x:%x:%x.%x%n",
-				&seg, &bus, &slot, &func, &count) != 4) {
-				seg = 0;
-				if (sscanf(p, "%x:%x.%x%n",
-						&bus, &slot, &func, &count) != 3) {
-					/* Invalid format */
-					printk(KERN_ERR "PCI: Can't parse resource_alignment parameter: %s\n",
-						p);
-					break;
-				}
-			}
-			p += count;
-			if (seg == pci_domain_nr(dev->bus) &&
-				bus == dev->bus->number &&
-				slot == PCI_SLOT(dev->devfn) &&
-				func == PCI_FUNC(dev->devfn)) {
-				*resize = true;
-				if (align_order == -1)
-					align = PAGE_SIZE;
-				else
-					align = 1 << align_order;
-				/* Found */
-				break;
-			}
+
+		ret = pci_dev_str_match(dev, p, &p);
+		if (ret == 1) {
+			*resize = true;
+			if (align_order == -1)
+				align = PAGE_SIZE;
+			else
+				align = 1 << align_order;
+			break;
+		} else if (ret < 0) {
+			pr_err("PCI: Can't parse resource_alignment parameter: %s\n",
+			       p);
+			break;
 		}
+
 		if (*p != ';' && *p != ',') {
 			/* End of param or invalid format */
 			break;
-- 
2.11.0

[PATCH v8 2/4] PCI: Allow specifying devices using a base bus and path of devfns

[Logan Gunthorpe]

When specifying PCI devices on the kernel command line using a
BDF, the bus numbers can change when adding or replacing a device,
changing motherboard firmware, or applying kernel parameters like
pci=assign-buses. When this happens, it is usually undesirable to
apply whatever command line tweak to the wrong device.

Therefore, it is useful to be able to specify devices with a base
bus number and the path of devfns needed to get to it. (Similar to
the "device scope" structure in the Intel VT-d spec, Section 8.3.1.)

Thus, we add an option to specify devices in the following format:

[<domain>:]<bus>:<slot>.<func>[/<slot>.<func>]*

The path can be any segment within the PCI hierarchy of any length and
determined through the use of 'lspci -t'. When specified this way, it is
less likely that a renumbered bus will result in a valid device specification
and the tweak won't be applied to the wrong device.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Stephen Bates <sbates@raithlin.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
---
 Documentation/admin-guide/kernel-parameters.txt |   8 +-
 drivers/pci/pci.c                               | 117 ++++++++++++++++++++----
 2 files changed, 103 insertions(+), 22 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 5cc215870ee1..1fdd1ef03984 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3000,7 +3000,7 @@
 				or a set of devices (<pci_dev>). These are
 				specified in one of the following formats:
 
-				[<domain>:]<bus>:<slot>.<func>
+				[<domain>:]<bus>:<slot>.<func>[/<slot>.<func>]*
 				pci:<vendor>:<device>[:<subvendor>:<subdevice>]
 
 				Note: the first format specifies a PCI
@@ -3009,7 +3009,11 @@
 				firmware changes, or due to changes caused
 				by other kernel parameters. If the
 				domain is left unspecified, it is
-				taken to be zero. The second format
+				taken to be zero. Optionally, a path
+				to a device through multiple slot/function
+				addresses can be specified after the base
+				address (this is more robust against
+				renumbering issues). The second format
 				selects devices using IDs from the
 				configuration space which may match multiple
 				devices in the system.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index a6e5d195cbac..7356039a1ae7 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -192,6 +192,89 @@ EXPORT_SYMBOL_GPL(pci_ioremap_wc_bar);
 #endif
 
 /**
+ * pci_dev_str_match_path - test if a path string matches a device
+ * @dev:    the PCI device to test
+ * @p:      string to match the device against
+ * @endptr: pointer to the string after the match
+ *
+ * Test if a string (typically from a kernel parameter) formatted as a
+ * path of slot/function addresses matches a PCI device. The string must
+ * be of the form:
+ *
+ *   [<domain>:]<bus>:<slot>.<func>[/<slot>.<func>]*
+ *
+ * A path for a device can be obtained using 'lspci -t'. Using a path
+ * is more robust against bus renumbering than using only a single bus,
+ * slot and function address.
+ *
+ * Returns 1 if the string matches the device, 0 if it does not and
+ * a negative error code if it fails to parse the string.
+ */
+static int pci_dev_str_match_path(struct pci_dev *dev, const char *path,
+				  const char **endptr)
+{
+	int ret;
+	int seg, bus, slot, func;
+	char *wpath, *p;
+	char end;
+
+	*endptr = strchrnul(path, ';');
+
+	wpath = kmemdup_nul(path, *endptr - path, GFP_KERNEL);
+	if (!wpath)
+		return -ENOMEM;
+
+	while (1) {
+		p = strrchr(wpath, '/');
+		if (!p)
+			break;
+		ret = sscanf(p, "/%x.%x%c", &slot, &func, &end);
+		if (ret != 2) {
+			ret = -EINVAL;
+			goto free_and_exit;
+		}
+
+		if (dev->devfn != PCI_DEVFN(slot, func)) {
+			ret = 0;
+			goto free_and_exit;
+		}
+
+		/*
+		 * Note: we don't need to get a reference to the upstream
+		 * bridge because we hold a reference to the top level
+		 * device which should hold a reference to the bridge,
+		 * and so on.
+		 */
+		dev = pci_upstream_bridge(dev);
+		if (!dev) {
+			ret = 0;
+			goto free_and_exit;
+		}
+
+		*p = 0;
+	}
+
+	ret = sscanf(wpath, "%x:%x:%x.%x%c", &seg, &bus, &slot,
+		     &func, &end);
+	if (ret != 4) {
+		seg = 0;
+		ret = sscanf(wpath, "%x:%x.%x%c", &bus, &slot, &func, &end);
+		if (ret != 3) {
+			ret = -EINVAL;
+			goto free_and_exit;
+		}
+	}
+
+	ret = (seg == pci_domain_nr(dev->bus) &&
+	       bus == dev->bus->number &&
+	       dev->devfn == PCI_DEVFN(slot, func));
+
+free_and_exit:
+	kfree(wpath);
+	return ret;
+}
+
+/**
  * pci_dev_str_match - test if a string matches a device
  * @dev:    the PCI device to test
  * @p:      string to match the device against
@@ -200,13 +283,16 @@ EXPORT_SYMBOL_GPL(pci_ioremap_wc_bar);
  * Test if a string (typically from a kernel parameter) matches a specified
  * PCI device. The string may be of one of the following formats:
  *
- *   [<domain>:]<bus>:<slot>.<func>
+ *   [<domain>:]<bus>:<slot>.<func>[/<slot>.<func>]*
  *   pci:<vendor>:<device>[:<subvendor>:<subdevice>]
  *
  * The first format specifies a PCI bus/slot/function address which
  * may change if new hardware is inserted, if motherboard firmware changes,
  * or due to changes caused in kernel parameters. If the domain is
- * left unspecified, it is taken to be 0.
+ * left unspecified, it is taken to be 0. In order to be robust against
+ * bus renumbering issues, a path of PCI slot/function numbers may be used
+ * to address the specific device. The path for a device can be determined
+ * through the use of 'lspci -t'.
  *
  * The second format matches devices using IDs in the configuration
  * space which may match multiple devices in the system. A value of 0
@@ -222,7 +308,7 @@ static int pci_dev_str_match(struct pci_dev *dev, const char *p,
 			     const char **endptr)
 {
 	int ret;
-	int seg, bus, slot, func, count;
+	int count;
 	unsigned short vendor, device, subsystem_vendor, subsystem_device;
 
 	if (strncmp(p, "pci:", 4) == 0) {
@@ -248,25 +334,16 @@ static int pci_dev_str_match(struct pci_dev *dev, const char *p,
 		    (!subsystem_device ||
 			    subsystem_device == dev->subsystem_device))
 			goto found;
-
 	} else {
-		/* PCI Bus,Slot,Function ids are specified */
-		ret = sscanf(p, "%x:%x:%x.%x%n", &seg, &bus, &slot,
-			     &func, &count);
-		if (ret != 4) {
-			seg = 0;
-			ret = sscanf(p, "%x:%x.%x%n", &bus, &slot,
-				     &func, &count);
-			if (ret != 3)
-				return -EINVAL;
-		}
-
-		p += count;
+		/*
+		 * PCI Bus,Slot,Function ids are specified
+		 *  (optionally, may include a path of devfns following it)
+		 */
 
-		if (seg == pci_domain_nr(dev->bus) &&
-		    bus == dev->bus->number &&
-		    slot == PCI_SLOT(dev->devfn) &&
-		    func == PCI_FUNC(dev->devfn))
+		ret = pci_dev_str_match_path(dev, p, &p);
+		if (ret < 0)
+			return ret;
+		else if (ret)
 			goto found;
 	}
 
-- 
2.11.0

[PATCH v8 3/4] PCI: Introduce disable_acs_redir quirk

[Logan Gunthorpe]

Intel SPT PCH hardware has an implementation of the ACS bits that
does not comply with the PCI express standard. To deal with this
the existing code has an enable_acs() quirk for the hardware.

In order to be able to correctly disable the ACS redirect bits for
all hardware we need an analagous quirk to disable those bits.

This adds the function pci_dev_specific_disable_acs_redir() which
behaves similarly to pci_dev_specific_enable_acs() but uses a new
function pointer for quirks which disables the ACS redirect bits.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
---
 drivers/pci/quirks.c | 78 ++++++++++++++++++++++++++++++++++++++++++++--------
 include/linux/pci.h  |  5 ++++
 2 files changed, 71 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index f439de848658..414b22dc06b8 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4553,27 +4553,81 @@ static int pci_quirk_enable_intel_spt_pch_acs(struct pci_dev *dev)
 	return 0;
 }
 
-static const struct pci_dev_enable_acs {
+static int pci_quirk_disable_intel_spt_pch_acs_redir(struct pci_dev *dev)
+{
+	int pos;
+	u32 cap, ctrl;
+
+	if (!pci_quirk_intel_spt_pch_acs_match(dev))
+		return -ENOTTY;
+
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ACS);
+	if (!pos)
+		return -ENOTTY;
+
+	pci_read_config_dword(dev, pos + PCI_ACS_CAP, &cap);
+	pci_read_config_dword(dev, pos + INTEL_SPT_ACS_CTRL, &ctrl);
+
+	ctrl &= ~(PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC);
+
+	pci_write_config_dword(dev, pos + INTEL_SPT_ACS_CTRL, ctrl);
+
+	pci_info(dev, "Intel SPT PCH root port workaround: disabled ACS redirect\n");
+
+	return 0;
+}
+
+static const struct pci_dev_acs_ops {
 	u16 vendor;
 	u16 device;
 	int (*enable_acs)(struct pci_dev *dev);
-} pci_dev_enable_acs[] = {
-	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_enable_intel_pch_acs },
-	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_enable_intel_spt_pch_acs },
-	{ 0 }
+	int (*disable_acs_redir)(struct pci_dev *dev);
+} pci_dev_acs_ops[] = {
+	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
+	  .enable_acs = pci_quirk_enable_intel_pch_acs,
+	},
+	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
+	  .enable_acs = pci_quirk_enable_intel_spt_pch_acs,
+	  .disable_acs_redir = pci_quirk_disable_intel_spt_pch_acs_redir
+	},
 };
 
 int pci_dev_specific_enable_acs(struct pci_dev *dev)
 {
-	const struct pci_dev_enable_acs *i;
+	const struct pci_dev_acs_ops *p;
+	int i;
 	int ret;
 
-	for (i = pci_dev_enable_acs; i->enable_acs; i++) {
-		if ((i->vendor == dev->vendor ||
-		     i->vendor == (u16)PCI_ANY_ID) &&
-		    (i->device == dev->device ||
-		     i->device == (u16)PCI_ANY_ID)) {
-			ret = i->enable_acs(dev);
+	for (i = 0; i < ARRAY_SIZE(pci_dev_acs_ops); i++) {
+		p = &pci_dev_acs_ops[i];
+		if ((p->vendor == dev->vendor ||
+		     p->vendor == (u16)PCI_ANY_ID) &&
+		    (p->device == dev->device ||
+		     p->device == (u16)PCI_ANY_ID) &&
+		    p->enable_acs) {
+			ret = p->enable_acs(dev);
+			if (ret >= 0)
+				return ret;
+		}
+	}
+
+	return -ENOTTY;
+}
+
+int pci_dev_specific_disable_acs_redir(struct pci_dev *dev)
+{
+	const struct pci_dev_acs_ops *p;
+	int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(pci_dev_acs_ops); i++) {
+		p = &pci_dev_acs_ops[i];
+		if ((p->vendor == dev->vendor ||
+		     p->vendor == (u16)PCI_ANY_ID) &&
+		    (p->device == dev->device ||
+		     p->device == (u16)PCI_ANY_ID) &&
+		    p->disable_acs_redir) {
+			ret = p->disable_acs_redir(dev);
 			if (ret >= 0)
 				return ret;
 		}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index abd5d5e17aee..0a436ec4fef5 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1880,6 +1880,7 @@ enum pci_fixup_pass {
 void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev);
 int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags);
 int pci_dev_specific_enable_acs(struct pci_dev *dev);
+int pci_dev_specific_disable_acs_redir(struct pci_dev *dev);
 #else
 static inline void pci_fixup_device(enum pci_fixup_pass pass,
 				    struct pci_dev *dev) { }
@@ -1892,6 +1893,10 @@ static inline int pci_dev_specific_enable_acs(struct pci_dev *dev)
 {
 	return -ENOTTY;
 }
+static inline int pci_dev_specific_disable_acs_redir(struct pci_dev *dev)
+{
+	return -ENOTTY;
+}
 #endif
 
 void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
-- 
2.11.0

[PATCH v8 4/4] PCI: Introduce the disable_acs_redir parameter

[Logan Gunthorpe]

In order to support P2P traffic on a segment of the PCI hierarchy,
we must be able to disable the ACS redirect bits for select
PCI bridges. The bridges must be selected before the devices are
discovered by the kernel and the IOMMU groups created. Therefore,
a kernel command line parameter is created to specify devices
which must have their ACS bits disabled.

The new parameter takes a list of devices separated by a semicolon.
Each device specified will have it's ACS redirect bits disabled.
This is similar to the existing 'resource_alignment' parameter.

The ACS Request P2P Request Redirect, P2P Completion Redirect and P2P
Egress Control bits are disabled which is sufficient to always allow
passing P2P traffic uninterrupted. The bits are set after the kernel
(optionally) enables the ACS bits itself. It is also done regardless of
whether the kernel sets the bits or not seeing some BIOS firmware is known
to set the bits on boot.

If the user tries to disable the ACS redirct for a device without the
ACS capability, a warning is printed to dmesg.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Stephen Bates <sbates@raithlin.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  9 +++
 drivers/pci/pci.c                               | 76 ++++++++++++++++++++++++-
 2 files changed, 83 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1fdd1ef03984..ab19ed83f072 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3192,6 +3192,15 @@
 				Adding the window is slightly risky (it may
 				conflict with unreported devices), so this
 				taints the kernel.
+		disable_acs_redir=<pci_dev>[; ...]
+				Specify one or more PCI devices (in the format
+				specified above) separated by semicolons.
+				Each device specified will have the PCI ACS
+				redirect capabilities forced off which will
+				allow P2P traffic between devices through
+				bridges without forcing it upstream. Note:
+				this removes isolation between devices and
+				will make the IOMMU groups less granular.
 
 	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
 			Management.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7356039a1ae7..594e815a27ec 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2983,6 +2983,66 @@ void pci_request_acs(void)
 	pci_acs_enable = 1;
 }
 
+static const char *disable_acs_redir_param;
+
+/**
+ * pci_disable_acs_redir - disable ACS redirect capabilities
+ * @dev: the PCI device
+ *
+ * For only devices specified in the disable_acs_redir parameter.
+ */
+static void pci_disable_acs_redir(struct pci_dev *dev)
+{
+	int ret = 0;
+	const char *p;
+	int pos;
+	u16 ctrl;
+
+	if (!disable_acs_redir_param)
+		return;
+
+	p = disable_acs_redir_param;
+	while (*p) {
+		ret = pci_dev_str_match(dev, p, &p);
+		if (ret < 0) {
+			pr_info_once("PCI: Can't parse disable_acs_redir parameter: %s\n",
+				     disable_acs_redir_param);
+
+			break;
+		} else if (ret == 1) {
+			/* Found a match */
+			break;
+		}
+
+		if (*p != ';' && *p != ',') {
+			/* End of param or invalid format */
+			break;
+		}
+		p++;
+	}
+
+	if (ret != 1)
+		return;
+
+	if (!pci_dev_specific_disable_acs_redir(dev))
+		return;
+
+	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ACS);
+	if (!pos) {
+		pci_warn(dev, "cannot disable ACS redirect for this hardware as it does not have ACS capabilities\n");
+		return;
+	}
+
+	pci_read_config_word(dev, pos + PCI_ACS_CTRL, &ctrl);
+
+	/* P2P Request & Completion Redirect */
+	ctrl &= ~(PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC);
+
+	pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl);
+
+	pci_info(dev, "disabled ACS redirect\n");
+}
+
 /**
  * pci_std_enable_acs - enable ACS on devices using standard ACS capabilites
  * @dev: the PCI device
@@ -3022,12 +3082,22 @@ static void pci_std_enable_acs(struct pci_dev *dev)
 void pci_enable_acs(struct pci_dev *dev)
 {
 	if (!pci_acs_enable)
-		return;
+		goto disable_acs_redir;
 
 	if (!pci_dev_specific_enable_acs(dev))
-		return;
+		goto disable_acs_redir;
 
 	pci_std_enable_acs(dev);
+
+disable_acs_redir:
+	/*
+	 * Note: pci_disable_acs_redir() must be called even if
+	 * ACS is not enabled by the kernel because the firmware
+	 * may have unexpectedly set the flags. So if we are told
+	 * to disable it, we should always disable it after setting
+	 * the kernel's default preferences.
+	 */
+	pci_disable_acs_redir(dev);
 }
 
 static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)
@@ -6005,6 +6075,8 @@ static int __init pci_setup(char *str)
 				pcie_bus_config = PCIE_BUS_PEER2PEER;
 			} else if (!strncmp(str, "pcie_scan_all", 13)) {
 				pci_add_flags(PCI_SCAN_ALL_PCIE_DEVS);
+			} else if (!strncmp(str, "disable_acs_redir=", 18)) {
+				disable_acs_redir_param = str + 18;
 			} else {
 				printk(KERN_ERR "PCI: Unknown option `%s'\n",
 						str);
-- 
2.11.0

Re: [PATCH v8 0/4] Add parameter for disabling ACS redirection for P2P

[Logan Gunthorpe]

Hey,

Oops, I missed finishing this up before sending it sorry:

This is mostly a resend with Alex's tags collected. Bjorn, can you
please consider merging this? All patches have been reviewed and
accepted by Alex.

Thanks,

Logan

--

Changes since v7:
* Collected Alex's Reviewed-by Tags
* Rebased onto v4.18-rc7 (no conflicts)


On 30/07/18 10:18 AM, Logan Gunthorpe wrote:
> Changes since v6:
> * Fixed order of operations for device specific disable function as
>   noticed by Alex
> * Rebased onto v4.18-rc5 (no conflicts)
> 
> Changes since v5:
> * Add a quirk to handle the Intel SPT PCH case (as pointed out by Alex)
> * Warn in the case that we try to disable ACS redirect on a device
>   that doesn't have the ACS capability (also suggested by Alex)
> * Collect reviewed-by tag from Alex
> * Rebased onto v4.18-rc4 (no conflicts)
> 
> Changes since v4:
> * Fixed a couple documentation mistakes spotted by Randy
> 
> Changes since v3:
> * Removed some of the cruft that was copied from the resource_alignment
>   paramater (per Alex)
> * A number of docuemntation fixes as noticed by Alex and Willy
> 
> Changes since v2:
> * Rebased onto v4.18-rc1 (no conflicts)
> * Minor tweaks to the documentation per Andy
> * Removed the "path:" prefix and use the path parsing code
>   for simple devices (as it works the same). Per a suggestion from Alex
> 
> Changes since v1:
> * Reworked pci_dev_str_match_path using strrchr as suggested by Alex
> * Collected Christian's Acks
> 
> 
> Logan Gunthorpe (4):
>   PCI: Make specifying PCI devices in kernel parameters reusable
>   PCI: Allow specifying devices using a base bus and path of devfns
>   PCI: Introduce disable_acs_redir quirk
>   PCI: Introduce the disable_acs_redir parameter
> 
>  Documentation/admin-guide/kernel-parameters.txt |  41 +++-
>  drivers/pci/pci.c                               | 310 +++++++++++++++++++-----
>  drivers/pci/quirks.c                            |  78 +++++-
>  include/linux/pci.h                             |   5 +
>  4 files changed, 361 insertions(+), 73 deletions(-)
> 
> --
> 2.11.0
> 

Re: [PATCH v8 1/4] PCI: Make specifying PCI devices in kernel parameters reusable

[Bjorn Helgaas]

On Mon, Jul 30, 2018 at 10:18:37AM -0600, Logan Gunthorpe wrote:
> Separate out the code to match a PCI device with a string (typically
> originating from a kernel parameter) from the
> pci_specified_resource_alignment() function into its own helper
> function.
> 
> While we are at it, this change fixes the kernel style of the function
> (fixing a number of long lines and extra parentheses).
> 
> Additionally, make the analogous change to the kernel parameter
> documentation: Separating the description of how to specify a PCI device
> into it's own section at the head of the pci= parameter.
> 
> This patch should have no functional alterations.
> 
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Reviewed-by: Stephen Bates <sbates@raithlin.com>
> Acked-by: Christian König <christian.koenig@amd.com>
> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt |  28 ++++-
>  drivers/pci/pci.c                               | 157 ++++++++++++++++--------
>  2 files changed, 126 insertions(+), 59 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 533ff5c68970..5cc215870ee1 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2994,7 +2994,26 @@
>  			See header of drivers/block/paride/pcd.c.
>  			See also Documentation/blockdev/paride.txt.
>  
> -	pci=option[,option...]	[PCI] various PCI subsystem options:
> +	pci=option[,option...]	[PCI] various PCI subsystem options.
> +
> +				Some options herein operate on a specific device
> +				or a set of devices (<pci_dev>). These are
> +				specified in one of the following formats:
> +
> +				[<domain>:]<bus>:<slot>.<func>
> +				pci:<vendor>:<device>[:<subvendor>:<subdevice>]
> +
> +				Note: the first format specifies a PCI
> +				bus/slot/function address which may change

Unless you object, I'm going to change "slot" references like this to
"device" so they match "BDF" and the language in the spec, which uses
"slot" to refer to a physical slot and "device" when referring to
geographical device addresses.  I can do this when I apply these, so
no need for you to repost them.

Bjorn

Re: [PATCH v8 3/4] PCI: Introduce disable_acs_redir quirk

[Bjorn Helgaas]

On Mon, Jul 30, 2018 at 10:18:39AM -0600, Logan Gunthorpe wrote:
> Intel SPT PCH hardware has an implementation of the ACS bits that
> does not comply with the PCI express standard. To deal with this
> the existing code has an enable_acs() quirk for the hardware.
> 
> In order to be able to correctly disable the ACS redirect bits for
> all hardware we need an analagous quirk to disable those bits.
> 
> This adds the function pci_dev_specific_disable_acs_redir() which
> behaves similarly to pci_dev_specific_enable_acs() but uses a new
> function pointer for quirks which disables the ACS redirect bits.
> 
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> ...

> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index abd5d5e17aee..0a436ec4fef5 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1880,6 +1880,7 @@ enum pci_fixup_pass {
>  void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev);
>  int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags);
>  int pci_dev_specific_enable_acs(struct pci_dev *dev);
> +int pci_dev_specific_disable_acs_redir(struct pci_dev *dev);
>  #else
>  static inline void pci_fixup_device(enum pci_fixup_pass pass,
>  				    struct pci_dev *dev) { }
> @@ -1892,6 +1893,10 @@ static inline int pci_dev_specific_enable_acs(struct pci_dev *dev)
>  {
>  	return -ENOTTY;
>  }
> +static inline int pci_dev_specific_disable_acs_redir(struct pci_dev *dev)
> +{
> +	return -ENOTTY;
> +}

I assume these could go in drivers/pci/pci.h instead of
include/linux/pci.h?

I can do that (and add another patch to move the
pci_dev_specific_acs_enabled() and pci_dev_specific_enable_acs()
declarations, which also are only used inside drivers/pci) if you agree.

>  #endif
>  
>  void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
> -- 
> 2.11.0
> 

Re: [PATCH v8 1/4] PCI: Make specifying PCI devices in kernel parameters reusable

[Logan Gunthorpe]

On 09/08/18 03:15 PM, Bjorn Helgaas wrote:
>> @@ -2994,7 +2994,26 @@
>>  			See header of drivers/block/paride/pcd.c.
>>  			See also Documentation/blockdev/paride.txt.
>>  
>> -	pci=option[,option...]	[PCI] various PCI subsystem options:
>> +	pci=option[,option...]	[PCI] various PCI subsystem options.
>> +
>> +				Some options herein operate on a specific device
>> +				or a set of devices (<pci_dev>). These are
>> +				specified in one of the following formats:
>> +
>> +				[<domain>:]<bus>:<slot>.<func>
>> +				pci:<vendor>:<device>[:<subvendor>:<subdevice>]
>> +
>> +				Note: the first format specifies a PCI
>> +				bus/slot/function address which may change
> 
> Unless you object, I'm going to change "slot" references like this to
> "device" so they match "BDF" and the language in the spec, which uses
> "slot" to refer to a physical slot and "device" when referring to
> geographical device addresses.  I can do this when I apply these, so
> no need for you to repost them.

No objection. I never liked the "slot" reference but was trying to
remain consistent with what was there before. If I remember correctly
there's a bunch of places in the kernel that use slot as well.

Thanks,

Logan

Re: [PATCH v8 3/4] PCI: Introduce disable_acs_redir quirk

[Logan Gunthorpe]

On 09/08/18 03:17 PM, Bjorn Helgaas wrote:
> I assume these could go in drivers/pci/pci.h instead of
> include/linux/pci.h?

Yeah, I agree they'd be better suited in the local file. I just followed
what had already existed.

> I can do that (and add another patch to move the
> pci_dev_specific_acs_enabled() and pci_dev_specific_enable_acs()
> declarations, which also are only used inside drivers/pci) if you agree.

Sounds good to me.

Thanks,

Logan

Re: [PATCH v8 0/4] Add parameter for disabling ACS redirection for P2P

[Bjorn Helgaas]

On Mon, Jul 30, 2018 at 10:18:36AM -0600, Logan Gunthorpe wrote:
> Changes since v6:
> * Fixed order of operations for device specific disable function as
>   noticed by Alex
> * Rebased onto v4.18-rc5 (no conflicts)
> 
> Changes since v5:
> * Add a quirk to handle the Intel SPT PCH case (as pointed out by Alex)
> * Warn in the case that we try to disable ACS redirect on a device
>   that doesn't have the ACS capability (also suggested by Alex)
> * Collect reviewed-by tag from Alex
> * Rebased onto v4.18-rc4 (no conflicts)
> 
> Changes since v4:
> * Fixed a couple documentation mistakes spotted by Randy
> 
> Changes since v3:
> * Removed some of the cruft that was copied from the resource_alignment
>   paramater (per Alex)
> * A number of docuemntation fixes as noticed by Alex and Willy
> 
> Changes since v2:
> * Rebased onto v4.18-rc1 (no conflicts)
> * Minor tweaks to the documentation per Andy
> * Removed the "path:" prefix and use the path parsing code
>   for simple devices (as it works the same). Per a suggestion from Alex
> 
> Changes since v1:
> * Reworked pci_dev_str_match_path using strrchr as suggested by Alex
> * Collected Christian's Acks
> 
> 
> Logan Gunthorpe (4):
>   PCI: Make specifying PCI devices in kernel parameters reusable
>   PCI: Allow specifying devices using a base bus and path of devfns
>   PCI: Introduce disable_acs_redir quirk
>   PCI: Introduce the disable_acs_redir parameter
> 
>  Documentation/admin-guide/kernel-parameters.txt |  41 +++-
>  drivers/pci/pci.c                               | 310 +++++++++++++++++++-----
>  drivers/pci/quirks.c                            |  78 +++++-
>  include/linux/pci.h                             |   5 +
>  4 files changed, 361 insertions(+), 73 deletions(-)

I reorganized this a bit and split the quirk code into a couple
patches an put the result on my pci/peer-to-peer branch for v4.19.

I think the result is equivalent, but let me know if I made a mistake.

Bjorn

Re: [PATCH v8 0/4] Add parameter for disabling ACS redirection for P2P

[Logan Gunthorpe]

On 09/08/18 05:03 PM, Bjorn Helgaas wrote:

> I reorganized this a bit and split the quirk code into a couple
> patches an put the result on my pci/peer-to-peer branch for v4.19.
> 
> I think the result is equivalent, but let me know if I made a mistake.

Thanks for the cleanup, Bjorn. I reviewed the patches and did a quick
diff between my v8 and your branch. Everything looks good.

Logan