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Message-ID: <54FF8C5E.60007@ozlabs.ru>
Date: Wed, 11 Mar 2015 11:29:18 +1100
From: Alexey Kardashevskiy <aik@...abs.ru>
To: Alex Williamson <alex.williamson@...hat.com>
CC: linuxppc-dev@...ts.ozlabs.org,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 27/29] vfio: powerpc/spapr: powerpc/powernv/ioda2:
Rework ownership
On 03/11/2015 11:09 AM, Alex Williamson wrote:
> On Tue, 2015-03-10 at 01:07 +1100, Alexey Kardashevskiy wrote:
>> Before the IOMMU user would take control over the IOMMU table belonging to
>> a specific IOMMU group. This approach did not allow sharing tables between
>> IOMMU groups attached to the same container.
>>
>> This introduces a new IOMMU ownership flavour when the user can not
>> just control the existing IOMMU table but remove/create tables on demand.
>> If an IOMMU supports a set_ownership() callback, that lets the user have
>> full control over the IOMMU group. When the ownership is taken,
>> the platform code removes all the windows so the caller must create them.
>> Before returning the ownership back to the platform code, the user
>> has to unprogram and remove all the tables it created.
>
> We have no ability to enforce that requirement on the user. VFIO needs
> to do the cleanup if the user fails to.
Ah. Wrong commit log, VFIO always does cleanup (as I end my guests by c-a-x
most of the time :) ), will fix it.
>
>> Old-style ownership is still supported allowing VFIO to run on older
>> P5IOC2 and IODA IO controllers.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
>> ---
>> arch/powerpc/platforms/powernv/pci-ioda.c | 30 +++++++++++++++---
>> drivers/vfio/vfio_iommu_spapr_tce.c | 51 ++++++++++++++++++++++++-------
>> 2 files changed, 66 insertions(+), 15 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>> index 07857c4..afb6906 100644
>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>> @@ -1620,11 +1620,33 @@ static void pnv_ioda2_set_ownership(struct iommu_table_group *table_group,
>> {
>> struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,
>> table_group);
>> - if (enable)
>> - iommu_take_ownership(table_group);
>> - else
>> - iommu_release_ownership(table_group);
>> + if (enable) {
>> + pnv_pci_ioda2_unset_window(&pe->table_group, 0);
>> + pnv_pci_free_table(&pe->table_group.tables[0]);
>> + } else {
>> + struct iommu_table *tbl = &pe->table_group.tables[0];
>> + int64_t rc;
>>
>> + rc = pnv_pci_ioda2_create_table(&pe->table_group, 0,
>> + IOMMU_PAGE_SHIFT_4K,
>> + pe->phb->ioda.m32_pci_base,
>> + POWERNV_IOMMU_DEFAULT_LEVELS, tbl);
>> + if (rc) {
>> + pe_err(pe, "Failed to create 32-bit TCE table, err %ld",
>> + rc);
>> + return;
>> + }
>> +
>> + iommu_init_table(tbl, pe->phb->hose->node);
>> +
>> + rc = pnv_pci_ioda2_set_window(&pe->table_group, 0, tbl);
>> + if (rc) {
>> + pe_err(pe, "Failed to configure 32-bit TCE table, err %ld\n",
>> + rc);
>> + pnv_pci_free_table(tbl);
>> + return;
>> + }
>> + }
>> pnv_pci_ioda2_set_bypass(pe, !enable);
>> }
>>
>> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
>> index d665ddc..3bc0645 100644
>> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
>> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
>> @@ -426,18 +426,11 @@ static int tce_iommu_clear(struct tce_container *container,
>> static void tce_iommu_release(void *iommu_data)
>> {
>> struct tce_container *container = iommu_data;
>> - struct iommu_table *tbl;
>> - struct iommu_table_group *table_group;
>>
>> WARN_ON(container->grp);
>>
>> - if (container->grp) {
>> - table_group = iommu_group_get_iommudata(container->grp);
>> - tbl = &table_group->tables[0];
>> - tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
>> -
>> + if (container->grp)
>> tce_iommu_detach_group(iommu_data, container->grp);
>> - }
>>
>> tce_mem_unregister_all(container);
>> tce_iommu_disable(container);
>> @@ -826,14 +819,24 @@ static int tce_iommu_attach_group(void *iommu_data,
>>
>> if (!table_group->ops || !table_group->ops->set_ownership) {
>> ret = iommu_take_ownership(table_group);
>> + } else if (!table_group->ops->create_table ||
>> + !table_group->ops->set_window) {
>> + WARN_ON_ONCE(1);
>> + ret = -EFAULT;
>> } else {
>> /*
>> * Disable iommu bypass, otherwise the user can DMA to all of
>> * our physical memory via the bypass window instead of just
>> * the pages that has been explicitly mapped into the iommu
>> */
>> + struct iommu_table tbltmp = { 0 }, *tbl = &tbltmp;
>> +
>> table_group->ops->set_ownership(table_group, true);
>> - ret = 0;
>> + ret = table_group->ops->create_table(table_group, 0,
>> + IOMMU_PAGE_SHIFT_4K,
>> + table_group->tce32_size, 1, tbl);
>> + if (!ret)
>> + ret = table_group->ops->set_window(table_group, 0, tbl);
>> }
>>
>> if (ret)
>> @@ -852,6 +855,7 @@ static void tce_iommu_detach_group(void *iommu_data,
>> {
>> struct tce_container *container = iommu_data;
>> struct iommu_table_group *table_group;
>> + long i;
>>
>> mutex_lock(&container->lock);
>> if (iommu_group != container->grp) {
>> @@ -875,10 +879,35 @@ static void tce_iommu_detach_group(void *iommu_data,
>> BUG_ON(!table_group);
>>
>> /* Kernel owns the device now, we can restore bypass */
>> - if (!table_group->ops || !table_group->ops->set_ownership)
>> + if (!table_group->ops || !table_group->ops->set_ownership) {
>> + for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
>> + struct iommu_table *tbl = &table_group->tables[i];
>> +
>> + if (!tbl->it_size)
>> + continue;
>> +
>> + if (!tbl->it_ops)
>> + goto unlock_exit;
>> + tce_iommu_clear(container, tbl,
>> + tbl->it_offset, tbl->it_size);
>> + }
>> iommu_release_ownership(table_group);
>> - else
>> + } else if (!table_group->ops->unset_window) {
>> + WARN_ON_ONCE(1);
>> + } else {
>> + for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
>> + struct iommu_table *tbl = &table_group->tables[i];
>> +
>> + table_group->ops->unset_window(table_group, i);
>> + tce_iommu_clear(container, tbl,
>> + tbl->it_offset, tbl->it_size);
>> +
>> + if (tbl->it_ops->free)
>> + tbl->it_ops->free(tbl);
>> + }
>> +
>> table_group->ops->set_ownership(table_group, false);
>> + }
>>
>> unlock_exit:
>>
>
>
>
--
Alexey
--
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