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

From: Benjamin Herrenschmidt <[email-masked]>
Date: Tue, 20 May 2014 08:51:59 +1000

On Mon, 2014-05-19 at 16:33 -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.
> 
> 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.

Right, I don't understand why we need that mapping for base EEH. The
VFIO fd owns the PE, it can do operations on that PE, it doesn't need to
know the guest token/address.

Only when we start doing in-kernel acceleration of RTAS do we need that
sort of mapping established, which we'll be able to do via something
akin to what we did with TCEs to ensure we validate that we have
ownership of the physical device.

But let's proceed step by step. First, have something that is strictly
EEH from qemu RTAS to VFIO via ioctl, and that requires no mapping of
any sort.

Cheers,
Ben.

> > 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?
> 
> > +	/* 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.
> 
> > +
> > +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.
> 
> > +		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.
> 
> > +		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.
> 
> > +		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.
> 
> > +		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.
> 
> > +	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?
> 
> > +
> > +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 */
> 
>