Commit f5b16b80 authored by Nicolin Chen's avatar Nicolin Chen Committed by Joerg Roedel
Browse files

PCI: Suspend iommu function prior to resetting a device 



PCIe permits a device to ignore ATS invalidation TLPs while processing a
reset. This creates a problem visible to the OS where an ATS invalidation
command will time out: e.g. an SVA domain will have no coordination with a
reset event and can racily issue ATS invalidations to a resetting device.

The PCIe r6.0, sec 10.3.1 IMPLEMENTATION NOTE recommends SW to disable and
block ATS before initiating a Function Level Reset. It also mentions that
other reset methods could have the same vulnerability as well.

The IOMMU subsystem provides pci_dev_reset_iommu_prepare/done() callback
helpers for this matter. Use them in all the existing reset functions.

This will attach the device to its iommu_group->blocking_domain during the
device reset, so as to allow IOMMU driver to:
 - invoke pci_disable_ats() and pci_enable_ats(), if necessary
 - wait for all ATS invalidations to complete
 - stop issuing new ATS invalidations
 - fence any incoming ATS queries

Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Tested-by: default avatarDheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Signed-off-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent c279e839

drivers/pci/pci-acpi.c

+11 −2
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 


#include <linux/delay.h>

#include <linux/init.h>

#include <linux/iommu.h>

#include <linux/irqdomain.h>

#include <linux/pci.h>

#include <linux/msi.h>
@@ -971,6 +972,7 @@ void pci_set_acpi_fwnode(struct pci_dev *dev) 
int pci_dev_acpi_reset(struct pci_dev *dev, bool probe)

{

	acpi_handle handle = ACPI_HANDLE(&dev->dev);

	int ret;



	if (!handle || !acpi_has_method(handle, "_RST"))

		return -ENOTTY;
@@ -978,12 +980,19 @@ int pci_dev_acpi_reset(struct pci_dev *dev, bool probe) 
	if (probe)

		return 0;



	ret = pci_dev_reset_iommu_prepare(dev);

	if (ret) {

		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", ret);

		return ret;

	}



	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_RST", NULL, NULL))) {

		pci_warn(dev, "ACPI _RST failed\n");

		return -ENOTTY;

		ret = -ENOTTY;

	}



	return 0;

	pci_dev_reset_iommu_done(dev);

	return ret;

}



bool acpi_pci_power_manageable(struct pci_dev *dev)

drivers/pci/pci.c

+58 −7
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/delay.h>

#include <linux/dmi.h>

#include <linux/init.h>

#include <linux/iommu.h>

#include <linux/msi.h>

#include <linux/of.h>

#include <linux/pci.h>
@@ -25,6 +26,7 @@ 
#include <linux/logic_pio.h>

#include <linux/device.h>

#include <linux/pm_runtime.h>

#include <linux/pci-ats.h>

#include <linux/pci_hotplug.h>

#include <linux/vmalloc.h>

#include <asm/dma.h>
@@ -4330,13 +4332,22 @@ EXPORT_SYMBOL(pci_wait_for_pending_transaction); 
 */

int pcie_flr(struct pci_dev *dev)

{

	int ret;



	if (!pci_wait_for_pending_transaction(dev))

		pci_err(dev, "timed out waiting for pending transaction; performing function level reset anyway\n");



	/* Have to call it after waiting for pending DMA transaction */

	ret = pci_dev_reset_iommu_prepare(dev);

	if (ret) {

		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", ret);

		return ret;

	}



	pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_BCR_FLR);



	if (dev->imm_ready)

		return 0;

		goto done;



	/*

	 * Per PCIe r4.0, sec 6.6.2, a device must complete an FLR within
@@ -4345,7 +4356,10 @@ int pcie_flr(struct pci_dev *dev) 
	 */

	msleep(100);



	return pci_dev_wait(dev, "FLR", PCIE_RESET_READY_POLL_MS);

	ret = pci_dev_wait(dev, "FLR", PCIE_RESET_READY_POLL_MS);

done:

	pci_dev_reset_iommu_done(dev);

	return ret;

}

EXPORT_SYMBOL_GPL(pcie_flr);
@@ -4373,6 +4387,7 @@ EXPORT_SYMBOL_GPL(pcie_reset_flr); 


static int pci_af_flr(struct pci_dev *dev, bool probe)

{

	int ret;

	int pos;

	u8 cap;
@@ -4399,10 +4414,17 @@ static int pci_af_flr(struct pci_dev *dev, bool probe) 
				 PCI_AF_STATUS_TP << 8))

		pci_err(dev, "timed out waiting for pending transaction; performing AF function level reset anyway\n");



	/* Have to call it after waiting for pending DMA transaction */

	ret = pci_dev_reset_iommu_prepare(dev);

	if (ret) {

		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", ret);

		return ret;

	}



	pci_write_config_byte(dev, pos + PCI_AF_CTRL, PCI_AF_CTRL_FLR);



	if (dev->imm_ready)

		return 0;

		goto done;



	/*

	 * Per Advanced Capabilities for Conventional PCI ECN, 13 April 2006,
@@ -4412,7 +4434,10 @@ static int pci_af_flr(struct pci_dev *dev, bool probe) 
	 */

	msleep(100);



	return pci_dev_wait(dev, "AF_FLR", PCIE_RESET_READY_POLL_MS);

	ret = pci_dev_wait(dev, "AF_FLR", PCIE_RESET_READY_POLL_MS);

done:

	pci_dev_reset_iommu_done(dev);

	return ret;

}



/**
@@ -4433,6 +4458,7 @@ static int pci_af_flr(struct pci_dev *dev, bool probe) 
static int pci_pm_reset(struct pci_dev *dev, bool probe)

{

	u16 csr;

	int ret;



	if (!dev->pm_cap || dev->dev_flags & PCI_DEV_FLAGS_NO_PM_RESET)

		return -ENOTTY;
@@ -4447,6 +4473,12 @@ static int pci_pm_reset(struct pci_dev *dev, bool probe) 
	if (dev->current_state != PCI_D0)

		return -EINVAL;



	ret = pci_dev_reset_iommu_prepare(dev);

	if (ret) {

		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", ret);

		return ret;

	}



	csr &= ~PCI_PM_CTRL_STATE_MASK;

	csr |= PCI_D3hot;

	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, csr);
@@ -4457,7 +4489,9 @@ static int pci_pm_reset(struct pci_dev *dev, bool probe) 
	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, csr);

	pci_dev_d3_sleep(dev);



	return pci_dev_wait(dev, "PM D3hot->D0", PCIE_RESET_READY_POLL_MS);

	ret = pci_dev_wait(dev, "PM D3hot->D0", PCIE_RESET_READY_POLL_MS);

	pci_dev_reset_iommu_done(dev);

	return ret;

}



/**
@@ -4885,10 +4919,20 @@ static int pci_reset_bus_function(struct pci_dev *dev, bool probe) 
		return -ENOTTY;

	}



	rc = pci_dev_reset_iommu_prepare(dev);

	if (rc) {

		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", rc);

		return rc;

	}



	rc = pci_dev_reset_slot_function(dev, probe);

	if (rc != -ENOTTY)

		goto done;



	rc = pci_parent_bus_reset(dev, probe);

done:

	pci_dev_reset_iommu_done(dev);

	return rc;

	return pci_parent_bus_reset(dev, probe);

}



static int cxl_reset_bus_function(struct pci_dev *dev, bool probe)
@@ -4912,6 +4956,12 @@ static int cxl_reset_bus_function(struct pci_dev *dev, bool probe) 
	if (rc)

		return -ENOTTY;



	rc = pci_dev_reset_iommu_prepare(dev);

	if (rc) {

		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", rc);

		return rc;

	}



	if (reg & PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR) {

		val = reg;

	} else {
@@ -4926,6 +4976,7 @@ static int cxl_reset_bus_function(struct pci_dev *dev, bool probe) 
		pci_write_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL,

				      reg);



	pci_dev_reset_iommu_done(dev);

	return rc;

}

drivers/pci/quirks.c

+18 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <linux/pci.h>

#include <linux/isa-dma.h> /* isa_dma_bridge_buggy */

#include <linux/init.h>

#include <linux/iommu.h>

#include <linux/delay.h>

#include <linux/acpi.h>

#include <linux/dmi.h>
@@ -4228,6 +4229,22 @@ static const struct pci_dev_reset_methods pci_dev_reset_methods[] = { 
	{ 0 }

};



static int __pci_dev_specific_reset(struct pci_dev *dev, bool probe,

				    const struct pci_dev_reset_methods *i)

{

	int ret;



	ret = pci_dev_reset_iommu_prepare(dev);

	if (ret) {

		pci_err(dev, "failed to stop IOMMU for a PCI reset: %d\n", ret);

		return ret;

	}



	ret = i->reset(dev, probe);

	pci_dev_reset_iommu_done(dev);

	return ret;

}



/*

 * These device-specific reset methods are here rather than in a driver

 * because when a host assigns a device to a guest VM, the host may need
@@ -4242,7 +4259,7 @@ int pci_dev_specific_reset(struct pci_dev *dev, bool probe) 
		     i->vendor == (u16)PCI_ANY_ID) &&

		    (i->device == dev->device ||

		     i->device == (u16)PCI_ANY_ID))

			return i->reset(dev, probe);

			return __pci_dev_specific_reset(dev, probe, i);

	}



	return -ENOTTY;