Subject: Re: [PATCH 3/8] drivers/vfio: New IOCTL command VFIO_EEH_INFO

From: Gavin Shan <[email-masked]>
Date: Tue, 20 May 2014 10:22:08 +1000

On Mon, May 19, 2014 at 04:33:10PM -0600, Alex Williamson wrote:
>On Wed, 2014-05-14 at 14:11 +1000, Gavin Shan wrote:
>> The patch adds new IOCTL command VFIO_EEH_INFO to VFIO container
>> to support EEH functionality for PCI devices, which have been
>> passed from host to guest via VFIO.

Thanks for your comments, Alex.W :-)

>
>Some comments throughout, but overall this seems to forgo every bit of
>the device ownership and protection model used by VFIO and lets the user
>pick arbitrary host devices and do various operations, mostly unchecked.
>That's not acceptable.
>

As what I replied to patch[2], I'm going to let VFIO-PCI-dev fd handle
the newly introduced IOCTL command. That way, we should follow the VFIO
design principles (ownership and protection) because VFIO-PCI-dev fd
is owned by QEMU process usually.

Also, the address mapping maintained in EEH will be removed.

>> Signed-off-by: Gavin Shan <[email-masked]>
>> ---
>>  arch/powerpc/platforms/powernv/Makefile   |   1 +
>>  arch/powerpc/platforms/powernv/eeh-vfio.c | 593 ++++++++++++++++++++++++++++++
>>  drivers/vfio/vfio_iommu_spapr_tce.c       |  12 +
>>  include/uapi/linux/vfio.h                 |  57 +++
>>  4 files changed, 663 insertions(+)
>>  create mode 100644 arch/powerpc/platforms/powernv/eeh-vfio.c
>> 
>> diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
>> index 63cebb9..2b15a03 100644
>> --- a/arch/powerpc/platforms/powernv/Makefile
>> +++ b/arch/powerpc/platforms/powernv/Makefile
>> @@ -6,5 +6,6 @@ obj-y			+= opal-msglog.o
>>  obj-$(CONFIG_SMP)	+= smp.o
>>  obj-$(CONFIG_PCI)	+= pci.o pci-p5ioc2.o pci-ioda.o
>>  obj-$(CONFIG_EEH)	+= eeh-ioda.o eeh-powernv.o
>> +obj-$(CONFIG_VFIO_EEH)	+= eeh-vfio.o
>>  obj-$(CONFIG_PPC_SCOM)	+= opal-xscom.o
>>  obj-$(CONFIG_MEMORY_FAILURE)	+= opal-memory-errors.o
>> diff --git a/arch/powerpc/platforms/powernv/eeh-vfio.c b/arch/powerpc/platforms/powernv/eeh-vfio.c
>> new file mode 100644
>> index 0000000..69d5f2d
>> --- /dev/null
>> +++ b/arch/powerpc/platforms/powernv/eeh-vfio.c
>> @@ -0,0 +1,593 @@
>> +/*
>> +  * The file intends to support EEH funtionality for those PCI devices,
>> +  * which have been passed through from host to guest via VFIO. So this
>> +  * file is naturally part of VFIO implementation on PowerNV platform.
>> +  *
>> +  * Copyright Benjamin Herrenschmidt & Gavin Shan, IBM Corporation 2014.
>> +  *
>> +  * This program is free software; you can redistribute it and/or modify
>> +  * it under the terms of the GNU General Public License as published by
>> +  * the Free Software Foundation; either version 2 of the License, or
>> +  * (at your option) any later version.
>> +  */
>> +
>> +#include <linux/init.h>
>> +#include <linux/io.h>
>> +#include <linux/irq.h>
>> +#include <linux/kernel.h>
>> +#include <linux/kvm_host.h>
>> +#include <linux/msi.h>
>> +#include <linux/pci.h>
>> +#include <linux/string.h>
>> +#include <linux/vfio.h>
>> +
>> +#include <asm/eeh.h>
>> +#include <asm/eeh_event.h>
>> +#include <asm/io.h>
>> +#include <asm/iommu.h>
>> +#include <asm/opal.h>
>> +#include <asm/msi_bitmap.h>
>> +#include <asm/pci-bridge.h>
>> +#include <asm/ppc-pci.h>
>> +#include <asm/tce.h>
>> +#include <asm/uaccess.h>
>> +
>> +#include "powernv.h"
>> +#include "pci.h"
>> +
>> +static int powernv_eeh_vfio_map(struct vfio_eeh_info *info)
>> +{
>> +	struct pci_bus *bus, *pe_bus;
>> +	struct pci_dev *pdev;
>> +	struct eeh_dev *edev;
>> +	struct eeh_pe *pe;
>> +	int domain, bus_no, devfn;
>> +
>> +	/* Host address */
>> +	domain = info->map.host_domain;
>> +	bus_no = (info->map.host_cfg_addr >> 8) & 0xff;
>> +	devfn = info->map.host_cfg_addr & 0xff;
>
>Where are we validating that the user has any legitimate claim to be
>touching this device?
>

I'll let VFIO-PCI-dev fd handle the IOCTL command. With that, we shouldn't
have the problem.

>> +	/* Find PCI bus */
>> +	bus = pci_find_bus(domain, bus_no);
>> +	if (!bus) {
>> +		pr_warn("%s: PCI bus %04x:%02x not found\n",
>> +			__func__, domain, bus_no);
>> +		return -ENODEV;
>> +	}
>> +
>> +	/* Find PCI device */
>> +	pdev = pci_get_slot(bus, devfn);
>> +	if (!pdev) {
>> +		pr_warn("%s: PCI device %04x:%02x:%02x.%01x not found\n",
>> +			__func__, domain, bus_no,
>> +			PCI_SLOT(devfn), PCI_FUNC(devfn));
>> +		return -ENODEV;
>> +	}
>> +
>> +	/* No EEH device - almost impossible */
>> +	edev = pci_dev_to_eeh_dev(pdev);
>> +	if (unlikely(!edev)) {
>> +		pci_dev_put(pdev);
>> +		pr_warn("%s: No EEH dev for PCI device %s\n",
>> +			__func__, pci_name(pdev));
>> +		return -ENODEV;
>> +	}
>> +
>> +	/* Doesn't support PE migration between different PHBs */
>> +	pe = edev->pe;
>> +	if (!eeh_pe_passed(pe)) {
>> +		pe_bus = eeh_pe_bus_get(pe);
>> +		BUG_ON(!pe_bus);
>
>Can a user trigger this maliciously?
>
>> +
>> +		/* PE# has format 00BBSS00 */
>> +		pe->guest_addr.buid    = info->map.guest_buid;
>> +		pe->guest_addr.pe_addr = pe_bus->number << 16;
>> +		eeh_pe_set_passed(pe, true);
>> +	} else if (pe->guest_addr.buid != info->map.guest_buid) {
>> +		pci_dev_put(pdev);
>> +		pr_warn("%s: Mismatched PHB BUID (0x%llx, 0x%llx)\n",
>> +			__func__, pe->guest_addr.buid, info->map.guest_buid);
>> +		return -EINVAL;
>> +	}
>> +
>> +	edev->guest_addr.buid = info->map.guest_buid;
>> +	edev->guest_addr.config_addr = info->map.guest_cfg_addr;
>> +	eeh_dev_set_passed(edev, true);
>> +
>> +	pr_debug("EEH: Host PCI dev %s to %llx-%02x:%02x.%01x\n",
>> +		 pci_name(pdev), info->map.guest_buid,
>> +		 (info->map.guest_cfg_addr >> 8) & 0xFF,
>> +		 PCI_SLOT(info->map.guest_cfg_addr & 0xFF),
>> +		 PCI_FUNC(info->map.guest_cfg_addr & 0xFF));
>> +
>> +	pci_dev_put(pdev);
>> +	return 0;
>> +}
>
>So the effect of this function is that a user gets to setup an arbitrary
>guest mapping for an arbitrary host device and associated pe.  Is that
>right?  It seems bad.
>

I'm going to remove this mapping in next revision.

>> +
>> +static int powernv_eeh_vfio_unmap(struct vfio_eeh_info *info)
>> +{
>> +	struct eeh_vfio_pci_addr addr;
>> +	struct pci_dev *pdev;
>> +	struct eeh_dev *edev, *tmp;
>> +	struct eeh_pe *pe;
>> +	bool passed;
>> +
>> +	/* Get EEH device */
>> +	addr.buid = info->unmap.buid;
>> +	addr.config_addr = info->unmap.cfg_addr;
>> +	edev = eeh_vfio_dev_get(&addr);
>
>eeh_vfio_dev_get() just looks for a "passed" dev and a match for a well
>known address space.  Seems very exploitable.
>
>> +	if (!edev) {
>> +		pr_warn("%s: Cannot find %llx:%02x:%02x.%01x\n",
>> +			__func__, info->unmap.buid,
>> +			(info->unmap.cfg_addr >> 8) & 0xFF,
>> +			PCI_SLOT(info->unmap.cfg_addr & 0xFF),
>> +			PCI_FUNC(info->unmap.cfg_addr & 0xFF));
>> +		return -ENODEV;
>> +	}
>> +
>> +	/* Return EEH device */
>> +	memset(&edev->guest_addr, 0, sizeof(edev->guest_addr));
>> +	eeh_dev_set_passed(edev, false);
>> +	pdev = eeh_dev_to_pci_dev(edev);
>> +	pr_debug("EEH: Host PCI dev %s returned\n",
>> +		 pdev ? pci_name(pdev) : "NULL");
>> +
>> +	/* Return PE if no EEH device is owned by guest */
>> +	pe = edev->pe;
>> +	passed = false;
>> +	eeh_pe_for_each_dev(pe, edev, tmp) {
>> +		pdev = eeh_dev_to_pci_dev(edev);
>> +		if (pdev && pdev->subordinate)
>> +			continue;
>> +
>> +		if (eeh_dev_passed(edev)) {
>> +			passed = true;
>> +			break;
>> +		}
>> +	}
>> +
>> +	if (!passed) {
>> +		memset(&pe->guest_addr, 0, sizeof(pe->guest_addr));
>> +		eeh_pe_set_passed(pe, false);
>> +		pr_debug("EEH: PHB#%x-PE#%x returned to host\n",
>> +			 pe->phb->global_number, pe->addr);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int powernv_eeh_vfio_set_option(struct vfio_eeh_info *info)
>> +{
>> +	struct pnv_phb *phb;
>> +	struct eeh_dev *edev;
>> +	struct eeh_pe *pe;
>> +	struct eeh_vfio_pci_addr addr;
>> +	int opcode = info->option.option;
>> +	int ret = 0;
>> +
>> +	/* Check opcode */
>> +	if (opcode < EEH_OPT_DISABLE || opcode > EEH_OPT_THAW_DMA) {
>> +		pr_warn("%s: opcode %d out of range (%d, %d)\n",
>> +			__func__, opcode, EEH_OPT_DISABLE, EEH_OPT_THAW_DMA);
>> +		ret = 3;
>
>Please don't make up arbitrary return values.
>

Nope, it will be turned to "-3" eventually by QEMU. That means "Invalid Parameter"
defined in PAPR spec.

The IOCTL command handler return 3 values:

< 0: Linux kernel error. For example, error from copy_from_user().
> 0: Error code to the EEH RTAS request, which will be returned to guest.
= 0: Success
 
>> +		goto out;
>> +	}
>> +
>> +	/* Option "enable" uses PCI config address */
>> +	if (opcode == EEH_OPT_ENABLE) {
>> +		addr.buid = info->option.buid;
>> +		addr.config_addr = (info->option.addr >> 8) & 0xFFFF;
>> +		edev = eeh_vfio_dev_get(&addr);
>> +		if (!edev) {
>> +			pr_warn("%s: Cannot find %llx:%02x:%02x.%01x\n",
>> +				__func__, addr.buid,
>> +				(addr.config_addr >> 8) & 0xFF,
>> +				PCI_SLOT(addr.config_addr & 0xFF),
>> +				PCI_FUNC(addr.config_addr & 0xFF));
>> +			ret = 7;
>> +			goto out;
>> +		}
>> +		phb = edev->phb->private_data;
>> +	} else {
>> +		addr.buid    = info->option.buid;
>> +		addr.pe_addr = info->option.addr;
>> +		pe = eeh_vfio_pe_get(&addr);
>> +		if (!pe) {
>> +			pr_warn("%s: Cannot find PE %llx:%x\n",
>> +				__func__, addr.buid, addr.pe_addr);
>> +			ret = 7;
>> +			goto out;
>> +		}
>> +		phb = pe->phb->private_data;
>> +	}
>> +
>> +	/* Insure that the EEH stuff has been initialized */
>> +	if (!(phb->flags & PNV_PHB_FLAG_EEH)) {
>> +		pr_warn("%s: EEH disabled on PHB#%d\n",
>> +			__func__, phb->hose->global_number);
>> +		ret = 7;
>> +		goto out;
>> +	}
>> +
>> +	/*
>> +	 * The EEH functionality has been enabled on all PEs
>> +	 * by default. So just return success. The same situation
>> +	 * would be applied while we disable EEH functionality.
>> +	 * However, the guest isn't expected to disable that
>> +	 * at all.
>> +	 */
>> +	if (opcode == EEH_OPT_DISABLE ||
>> +	    opcode == EEH_OPT_ENABLE) {
>> +		ret = 0;
>> +		goto out;
>> +	}
>> +
>> +	/*
>> +	 * Call into the IODA dependent backend in order
>> +	 * to enable DMA or MMIO for the indicated PE.
>> +	 */
>> +	if (phb->eeh_ops && phb->eeh_ops->set_option) {
>> +		if (phb->eeh_ops->set_option(pe, opcode)) {
>> +			pr_warn("%s: Failure from backend\n",
>> +				__func__);
>> +			ret = 1;
>> +		}
>> +	} else {
>> +		pr_warn("%s: Unsupported request\n",
>> +			__func__);
>> +		ret = 7;
>> +	}
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +static int powernv_eeh_vfio_get_addr(struct vfio_eeh_info *info)
>> +{
>> +	struct pnv_phb *phb;
>> +	struct eeh_dev *edev;
>> +	struct eeh_vfio_pci_addr addr;
>> +	int opcode = info->addr.option;
>> +	int ret = 0;
>> +
>> +	/* Check opcode */
>> +	if (opcode != 0 && opcode != 1) {
>> +		pr_warn("%s: opcode %d out of range (0, 1)\n",
>> +			__func__, opcode);
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +
>> +	/* Find EEH device */
>> +	addr.buid = info->addr.buid;
>> +	addr.config_addr = (info->addr.cfg_addr >> 8 ) & 0xFFFF;
>> +	edev = eeh_vfio_dev_get(&addr);
>> +	if (!edev) {
>> +		pr_warn("%s: Cannot find %llx:%02x:%02x.%01x\n",
>> +			__func__, addr.buid,
>> +			(addr.config_addr >> 8) & 0xFF,
>> +			PCI_SLOT(addr.config_addr & 0xFF),
>> +			PCI_FUNC(addr.config_addr & 0xFF));
>> +		ret = 7;
>> +		goto out;
>> +	}
>> +	phb = edev->phb->private_data;
>> +
>> +	/* EEH enabled ? */
>> +	if (!(phb->flags & PNV_PHB_FLAG_EEH)) {
>> +		pr_warn("%s: EEH disabled on PHB#%d\n",
>> +			__func__, phb->hose->global_number);
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +
>> +	/* EEH device passed ? */
>> +	if (!eeh_dev_passed(edev)) {
>> +		pr_warn("%s: EEH dev %llx:%02x:%02x.%01x owned by host\n",
>> +			__func__, addr.buid,
>> +			(addr.config_addr >> 8) & 0xFF,
>> +			PCI_SLOT(addr.config_addr & 0xFF),
>> +			PCI_FUNC(addr.config_addr & 0xFF));
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +
>> +	/*
>> +	 * Fill result according to opcode. We don't differentiate
>> +	 * PCI bus and device sensitive PE here.
>> +	 */
>> +	if (opcode == 0)
>> +		info->addr.ret = edev->pe->guest_addr.pe_addr;
>> +	else
>> +		info->addr.ret = 1;
>> +out:
>> +	return ret;
>> +}
>> +
>> +static int powernv_eeh_vfio_get_state(struct vfio_eeh_info *info)
>> +{
>> +	struct pnv_phb *phb;
>> +	struct eeh_pe *pe;
>> +	struct eeh_vfio_pci_addr addr;
>> +	int result, ret = 0;
>> +
>> +	/* Locate the PE */
>> +	addr.buid    = info->state.buid;
>> +	addr.pe_addr = info->state.pe_addr;
>> +	pe = eeh_vfio_pe_get(&addr);
>> +	if (!pe) {
>> +		pr_warn("%s: Cannot locate %llx:%x\n",
>> +			__func__, addr.buid, addr.pe_addr);
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +	phb = pe->phb->private_data;
>> +
>> +	/* EEH enabled ? */
>> +	if (!(phb->flags & PNV_PHB_FLAG_EEH)) {
>> +		pr_warn("%s: EEH disabled on PHB#%d\n",
>> +			__func__, phb->hose->global_number);
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +
>> +	/* Call to the IOC dependent function */
>> +	if (phb->eeh_ops && phb->eeh_ops->get_state) {
>> +		result = phb->eeh_ops->get_state(pe);
>> +
>> +		if (!(result & EEH_STATE_RESET_ACTIVE) &&
>> +		     (result & EEH_STATE_DMA_ENABLED) &&
>> +		     (result & EEH_STATE_MMIO_ENABLED))
>> +			info->state.state = 0;
>> +		else if (result & EEH_STATE_RESET_ACTIVE)
>> +			info->state.state = 1;
>> +		else if (!(result & EEH_STATE_RESET_ACTIVE) &&
>> +			 !(result & EEH_STATE_DMA_ENABLED) &&
>> +			 !(result & EEH_STATE_MMIO_ENABLED))
>> +			info->state.state = 2;
>> +		else if (!(result & EEH_STATE_RESET_ACTIVE) &&
>> +			 (result & EEH_STATE_DMA_ENABLED) &&
>> +			 !(result & EEH_STATE_MMIO_ENABLED))
>> +			info->state.state = 4;
>> +		else
>> +			info->state.state = 5;
>> +
>> +		ret = 0;
>> +	} else {
>> +		pr_warn("%s: Unsupported request\n", __func__);
>> +		ret = 3;
>> +	}
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +static int powernv_eeh_vfio_pe_reset(struct vfio_eeh_info *info)
>> +{
>> +	struct pnv_phb *phb;
>> +	struct eeh_pe *pe;
>> +	struct eeh_vfio_pci_addr addr;
>> +	int opcode = info->reset.option;
>> +	int ret = 0;
>> +
>> +	/* Check opcode */
>> +	if (opcode != EEH_RESET_DEACTIVATE &&
>> +	    opcode != EEH_RESET_HOT &&
>> +	    opcode != EEH_RESET_FUNDAMENTAL) {
>> +		pr_warn("%s: Unsupported opcode %d\n",
>> +			__func__, opcode);
>
>Console warnings are exploitable DoS attacks.
>

Yep. I'll change all pr_warn() to pr_debug() in next revision.

>> +		ret = 3;
>> +		goto out;
>> +	}
>> +
>> +	/* Locate the PE */
>> +	addr.buid    = info->reset.buid;
>> +	addr.pe_addr = info->reset.pe_addr;
>> +	pe = eeh_vfio_pe_get(&addr);
>> +	if (!pe) {
>> +		pr_warn("%s: Cannot locate %llx:%x\n",
>> +			__func__, addr.buid, addr.pe_addr);
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +	phb = pe->phb->private_data;
>> +
>> +	/* EEH enabled ? */
>> +	if (!(phb->flags & PNV_PHB_FLAG_EEH)) {
>> +		pr_warn("%s: EEH disabled on PHB#%d\n",
>> +			__func__, phb->hose->global_number);
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +
>> +	/* Call into the IODA dependent backend to do the reset */
>> +	if (!phb->eeh_ops ||
>> +	    !phb->eeh_ops->set_option ||
>> +	    !phb->eeh_ops->reset) {
>> +		pr_warn("%s: Unsupported request\n",
>> +			__func__);
>> +		ret = 7;
>> +	} else {
>> +		/*
>> +		 * The frozen PE might be caused by the mechanism called
>> +		 * PAPR error injection, which is supposed to be one-shot
>> +		 * without "sticky" bit as being stated by the spec. But
>> +		 * the reality isn't that, at least on P7IOC. So we have
>> +		 * to clear that to avoid recrusive error, which fails the
>> +		 * recovery eventually.
>> +		 */
>> +		if (opcode == EEH_RESET_DEACTIVATE)
>> +			opal_pci_reset(phb->opal_id,
>> +				       OPAL_PHB_ERROR,
>> +				       OPAL_ASSERT_RESET);
>> +
>> +		if (phb->eeh_ops->reset(pe, opcode)) {
>> +			pr_warn("%s: Failure from backend\n", __func__);
>> +			ret = 1;
>> +			goto out;
>> +		}
>> +
>> +		/*
>> +		 * The PE is still in frozen state and we need clear that.
>> +		 * It's good to clear frozen state after deassert to avoid
>> +		 * messy IO access during reset, which might cause recrusive
>> +		 * frozen PE.
>> +		 */
>> +		if (opcode == EEH_RESET_DEACTIVATE) {
>> +			if (phb->eeh_ops->set_option(pe, EEH_OPT_THAW_MMIO) ||
>> +			    phb->eeh_ops->set_option(pe, EEH_OPT_THAW_DMA)) {
>> +				pr_warn("%s: Cannot clear frozen state\n",
>> +					__func__);
>> +				ret = 1;
>> +			}
>> +
>> +			eeh_pe_state_clear(pe, EEH_PE_ISOLATED);
>> +		}
>> +	}
>> +
>> +out:
>> +	return ret;
>> +}
>> +
>> +static int powernv_eeh_vfio_pe_config(struct vfio_eeh_info *info)
>> +{
>> +	struct pnv_phb *phb;
>> +	struct eeh_pe *pe;
>> +	struct eeh_vfio_pci_addr addr;
>> +	int ret = 0;
>> +
>> +	/* Locate the PE */
>> +	addr.buid    = info->config.buid;
>> +	addr.pe_addr = info->config.pe_addr;
>> +	pe = eeh_vfio_pe_get(&addr);
>> +	if (!pe) {
>> +		pr_warn("%s: Cannot locate %llx:%x\n",
>> +			__func__, addr.buid, addr.pe_addr);
>> +		ret = 3;
>> +		goto out;
>> +	}
>> +	phb = pe->phb->private_data;
>> +
>> +	/* EEH enabled ? */
>> +	if (!(phb->flags & PNV_PHB_FLAG_EEH)) {
>> +		pr_warn("%s: EEH disabled on PHB#%d\n",
>> +			__func__, phb->hose->global_number);
>> +		ret = 3;
>> +		goto out;
>> +        }
>> +
>> +	/*
>> +	 * The access to PCI config space on VFIO device has some
>> +	 * limitations. Part of PCI config space, including BAR
>> +	 * registers are not readable and writable. So the guest
>> +	 * should have stale values for those registers and we have
>> +	 * to restore them in host side.
>> +	 */
>> +	eeh_pe_restore_bars(pe);
>> +out:
>> +	return ret;
>> +}
>> +
>> +void eeh_vfio_release(struct iommu_table *tbl)
>> +{
>> +	struct pnv_ioda_pe *pnv_pe = container_of(tbl, struct pnv_ioda_pe,
>> +						  tce32_table);
>> +	struct pnv_phb *phb = pnv_pe->phb;
>> +	struct eeh_pe *phb_pe, *pe;
>> +	struct eeh_dev dev, *edev, *tmp;
>> +
>> +	/* Find PHB PE */
>> +	phb_pe = eeh_phb_pe_get(phb->hose);
>> +	if (unlikely(!phb_pe)) {
>> +		pr_warn("%s: Cannot find PHB#%d PE\n",
>> +			__func__, phb->hose->global_number);
>> +		return;
>> +	}
>> +
>> +	/* Find PE */
>> +	memset(&dev, 0, sizeof(struct eeh_dev));
>> +	dev.phb = phb->hose;
>> +	dev.pe_config_addr = pnv_pe->pe_number;
>> +	pe = eeh_pe_get(&dev);
>> +	if (unlikely(!pe)) {
>> +		pr_warn("%s: Cannot find PE instance for PHB#%d-PE#%d\n",
>> +			__func__, phb->hose->global_number,
>> +			pnv_pe->pe_number);
>> +		return;
>> +	}
>> +
>> +	/* Release it to host */
>> +	if (!eeh_pe_passed(pe))
>> +		return;
>> +
>> +	eeh_pe_for_each_dev(pe, edev, tmp) {
>> +		if (!eeh_dev_passed(edev))
>> +			continue;
>> +
>> +		memset(&edev->guest_addr, 0, sizeof(edev->guest_addr));
>
>Is guest_addr = { 0 } not valid?  As agraf already mentioned, there are
>a number of issues with using a guest_address for a token.
>

For now, PHB BUID can't be "0". Originally, I was planing to have some code
in QEMU to have unique PHB BUID across the system so that guest_address could
be the unique token. But I'm going to remove the address mapping in next revision
as Alex.G suggested. 

>> +		eeh_dev_set_passed(edev, false);
>> +	}
>> +
>> +	memset(&pe->guest_addr, 0, sizeof(pe->guest_addr));
>> +	eeh_pe_set_passed(pe, false);
>> +}
>> +EXPORT_SYMBOL(eeh_vfio_release);
>> +
>> +int eeh_vfio_ioctl(unsigned long arg)
>> +{
>> +	struct vfio_eeh_info info;
>> +	int ret = -EINVAL;
>> +
>> +	/* Copy over user argument */
>> +	if (copy_from_user(&info, (void __user *)arg, sizeof(info))) {
>> +		pr_warn("%s: Cannot copy user argument 0x%lx\n",
>> +			__func__, arg);
>> +		return -EFAULT;
>> +	}
>> +
>> +	/* Sanity check */
>> +	if (info.argsz != sizeof(info)) {
>
>This breaks compatibility if you need to later add a new ops with a
>larger footprint.
>

Ok. I'll fix it in next revision. Thanks for pointing it out.

>> +		pr_warn("%s: Invalid argument size (%d, %ld)\n",
>> +			__func__, info.argsz, sizeof(info));
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* Route according to operation */
>> +	switch (info.op) {
>> +	case VFIO_EEH_OP_MAP:
>> +		ret = powernv_eeh_vfio_map(&info);
>> +		break;
>> +	case VFIO_EEH_OP_UNMAP:
>> +		ret = powernv_eeh_vfio_unmap(&info);
>> +		break;
>> +	case VFIO_EEH_OP_SET_OPTION:
>> +		ret = powernv_eeh_vfio_set_option(&info);
>> +		break;
>> +	case VFIO_EEH_OP_GET_ADDR:
>> +		ret = powernv_eeh_vfio_get_addr(&info);
>> +		break;
>> +	case VFIO_EEH_OP_GET_STATE:
>> +		ret = powernv_eeh_vfio_get_state(&info);
>> +		break;
>> +	case VFIO_EEH_OP_PE_RESET:
>> +		ret = powernv_eeh_vfio_pe_reset(&info);
>> +		break;
>> +	case VFIO_EEH_OP_PE_CONFIG:
>> +		ret = powernv_eeh_vfio_pe_config(&info);
>> +		break;
>> +	default:
>> +		pr_info("%s: Cannot handle op#%d\n",
>> +			__func__, info.op);
>> +	}
>> +
>> +	/* Copy data back */
>> +	if (!ret && copy_to_user((void __user *)arg, &info, sizeof(info))) {
>> +		pr_warn("%s: Cannot copy to user 0x%lx\n",
>> +			__func__, arg);
>> +		return -EFAULT;
>> +	}
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(eeh_vfio_ioctl);
>> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
>> index a84788b..c45dece 100644
>> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
>> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
>> @@ -26,6 +26,11 @@
>>  #define DRIVER_AUTHOR   "[email-masked]"
>>  #define DRIVER_DESC     "VFIO IOMMU SPAPR TCE"
>>  
>> +#ifdef CONFIG_VFIO_EEH
>> +extern void eeh_vfio_release(struct iommu_table *tbl);
>> +extern int eeh_vfio_ioctl(unsigned long arg);
>> +#endif
>> +
>>  static void tce_iommu_detach_group(void *iommu_data,
>>  		struct iommu_group *iommu_group);
>>  
>> @@ -283,6 +288,10 @@ static long tce_iommu_ioctl(void *iommu_data,
>>  		tce_iommu_disable(container);
>>  		mutex_unlock(&container->lock);
>>  		return 0;
>> +#ifdef CONFIG_VFIO_EEH
>
>I'm not a fan of all these #ifdefs, hide it in eeh_vfio_ioctl() and
>eeh_vfio_release() if needed.
>

Ok. Will do it in next revision.

>> +	case VFIO_EEH_INFO:
>> +		return eeh_vfio_ioctl(arg);
>> +#endif
>>  	}
>>  
>>  	return -ENOTTY;
>> @@ -342,6 +351,9 @@ static void tce_iommu_detach_group(void *iommu_data,
>>  		/* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
>>  				iommu_group_id(iommu_group), iommu_group); */
>>  		container->tbl = NULL;
>> +#ifdef CONFIG_VFIO_EEH
>> +		eeh_vfio_release(tbl);
>> +#endif
>>  		iommu_release_ownership(tbl);
>>  	}
>>  	mutex_unlock(&container->lock);
>> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
>> index cb9023d..1fd1bfb 100644
>> --- a/include/uapi/linux/vfio.h
>> +++ b/include/uapi/linux/vfio.h
>> @@ -455,6 +455,63 @@ struct vfio_iommu_spapr_tce_info {
>>  
>>  #define VFIO_IOMMU_SPAPR_TCE_GET_INFO	_IO(VFIO_TYPE, VFIO_BASE + 12)
>>  
>> +/*
>> + * The VFIO EEH info struct provides way to support EEH functionality
>> + * for PCI device that is passed from host to guest via VFIO.
>> + */
>> +#define VFIO_EEH_OP_MAP		0
>> +#define VFIO_EEH_OP_UNMAP	1
>> +#define VFIO_EEH_OP_SET_OPTION	2
>> +#define VFIO_EEH_OP_GET_ADDR	3
>> +#define VFIO_EEH_OP_GET_STATE	4
>> +#define VFIO_EEH_OP_PE_RESET	5
>> +#define VFIO_EEH_OP_PE_CONFIG	6
>
>Is this really an "info" ioctl?
>

Yeah, "VFIO_EEH_INFO" isn't a good name. How about to have "VFIO_EEH_HANDLER" ?

>> +
>> +struct vfio_eeh_info {
>> +	__u32 argsz;
>> +	__u32 op;
>> +
>> +	union {
>> +		struct vfio_eeh_map {
>> +			__u32 host_domain;
>> +			__u16 host_cfg_addr;
>> +			__u64 guest_buid;
>> +			__u16 guest_cfg_addr;
>> +		} map;
>> +		struct vfio_eeh_unmap {
>> +			__u64 buid;
>> +			__u16 cfg_addr;
>> +		} unmap;
>> +		struct vfio_eeh_set_option {
>> +			__u64 buid;
>> +			__u32 addr;
>> +			__u32 option;
>> +		} option;
>> +		struct vfio_eeh_pe_addr {
>> +			__u64 buid;
>> +			__u32 cfg_addr;
>> +			__u32 option;
>> +			__u32 ret;
>> +		} addr;
>> +		struct vfio_eeh_state {
>> +			__u64 buid;
>> +			__u32 pe_addr;
>> +			__u32 state;
>> +                } state;
>> +		struct vfio_eeh_reset {
>> +			__u64 buid;
>> +			__u32 pe_addr;
>> +			__u32 option;
>> +		} reset;
>> +		struct vfio_eeh_config {
>> +			__u64 buid;
>> +			__u32 pe_addr;
>> +		} config;
>> +	};
>> +};
>> +
>> +#define VFIO_EEH_INFO	_IO(VFIO_TYPE, VFIO_BASE + 21)
>> +
>>  /* ***************************************************************** */
>>  
>>  #endif /* _UAPIVFIO_H */

Thanks,
Gavin