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Date: Mon, 7 Nov 2016 16:16:19 -0700
From: Alex Williamson <alex.williamson@...hat.com>
To: Kirti Wankhede <kwankhede@...dia.com>
Cc: <pbonzini@...hat.com>, <kraxel@...hat.com>, <cjia@...dia.com>,
<qemu-devel@...gnu.org>, <kvm@...r.kernel.org>,
<kevin.tian@...el.com>, <jike.song@...el.com>,
<bjsdjshi@...ux.vnet.ibm.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 10/22] vfio iommu type1: Add support for mediated
devices
On Sat, 5 Nov 2016 02:40:44 +0530
Kirti Wankhede <kwankhede@...dia.com> wrote:
> VFIO IOMMU drivers are designed for the devices which are IOMMU capable.
> Mediated device only uses IOMMU APIs, the underlying hardware can be
> managed by an IOMMU domain.
>
> Aim of this change is:
> - To use most of the code of TYPE1 IOMMU driver for mediated devices
> - To support direct assigned device and mediated device in single module
>
> This change adds pin and unpin support for mediated device to TYPE1 IOMMU
> backend module. More details:
> - vfio_pin_pages() callback here uses task and address space of vfio_dma,
> that is, of the process who mapped that iova range.
> - Added pfn_list tracking logic to address space structure. All pages
> pinned through this interface are trached in its address space.
^ k
------------------------------------------|
> - Pinned pages list is used to verify unpinning request and to unpin
> remaining pages while detaching the group for that device.
> - Page accounting is updated to account in its address space where the
> pages are pinned/unpinned.
> - Accouting for mdev device is only done if there is no iommu capable
> domain in the container. When there is a direct device assigned to the
> container and that domain is iommu capable, all pages are already pinned
> during DMA_MAP.
> - Page accouting is updated on hot plug and unplug mdev device and pass
> through device.
>
> Tested by assigning below combinations of devices to a single VM:
> - GPU pass through only
> - vGPU device only
> - One GPU pass through and one vGPU device
> - Linux VM hot plug and unplug vGPU device while GPU pass through device
> exist
> - Linux VM hot plug and unplug GPU pass through device while vGPU device
> exist
>
> Signed-off-by: Kirti Wankhede <kwankhede@...dia.com>
> Signed-off-by: Neo Jia <cjia@...dia.com>
> Change-Id: I295d6f0f2e0579b8d9882bfd8fd5a4194b97bd9a
> ---
> drivers/vfio/vfio_iommu_type1.c | 538 +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 500 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 8d64528dcc22..e511073446a0 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -36,6 +36,7 @@
> #include <linux/uaccess.h>
> #include <linux/vfio.h>
> #include <linux/workqueue.h>
> +#include <linux/mdev.h>
>
> #define DRIVER_VERSION "0.2"
> #define DRIVER_AUTHOR "Alex Williamson <alex.williamson@...hat.com>"
> @@ -56,6 +57,7 @@ MODULE_PARM_DESC(disable_hugepages,
> struct vfio_iommu {
> struct list_head domain_list;
> struct list_head addr_space_list;
> + struct vfio_domain *external_domain; /* domain for external user */
> struct mutex lock;
> struct rb_root dma_list;
> bool v2;
> @@ -67,6 +69,9 @@ struct vfio_addr_space {
> struct mm_struct *mm;
> struct list_head next;
> atomic_t ref_count;
> + /* external user pinned pfns */
> + struct rb_root pfn_list; /* pinned Host pfn list */
> + struct mutex pfn_list_lock; /* mutex for pfn_list */
> };
>
> struct vfio_domain {
> @@ -83,6 +88,7 @@ struct vfio_dma {
> unsigned long vaddr; /* Process virtual addr */
> size_t size; /* Map size (bytes) */
> int prot; /* IOMMU_READ/WRITE */
> + bool iommu_mapped;
> struct vfio_addr_space *addr_space;
> struct task_struct *task;
> bool mlock_cap;
> @@ -94,6 +100,19 @@ struct vfio_group {
> };
>
> /*
> + * Guest RAM pinning working set or DMA target
> + */
> +struct vfio_pfn {
> + struct rb_node node;
> + unsigned long pfn; /* Host pfn */
> + int prot;
> + atomic_t ref_count;
> +};
> +
> +#define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \
> + (!list_empty(&iommu->domain_list))
> +
> +/*
> * This code handles mapping and unmapping of user data buffers
> * into DMA'ble space using the IOMMU
> */
> @@ -153,6 +172,93 @@ static struct vfio_addr_space *vfio_find_addr_space(struct vfio_iommu *iommu,
> return NULL;
> }
>
> +/*
> + * Helper Functions for host pfn list
> + */
> +static struct vfio_pfn *vfio_find_pfn(struct vfio_addr_space *addr_space,
> + unsigned long pfn)
> +{
> + struct vfio_pfn *vpfn;
> + struct rb_node *node = addr_space->pfn_list.rb_node;
> +
> + while (node) {
> + vpfn = rb_entry(node, struct vfio_pfn, node);
> +
> + if (pfn < vpfn->pfn)
> + node = node->rb_left;
> + else if (pfn > vpfn->pfn)
> + node = node->rb_right;
> + else
> + return vpfn;
> + }
> +
> + return NULL;
> +}
> +
> +static void vfio_link_pfn(struct vfio_addr_space *addr_space,
> + struct vfio_pfn *new)
> +{
> + struct rb_node **link, *parent = NULL;
> + struct vfio_pfn *vpfn;
> +
> + link = &addr_space->pfn_list.rb_node;
> + while (*link) {
> + parent = *link;
> + vpfn = rb_entry(parent, struct vfio_pfn, node);
> +
> + if (new->pfn < vpfn->pfn)
> + link = &(*link)->rb_left;
> + else
> + link = &(*link)->rb_right;
> + }
> +
> + rb_link_node(&new->node, parent, link);
> + rb_insert_color(&new->node, &addr_space->pfn_list);
> +}
> +
> +static void vfio_unlink_pfn(struct vfio_addr_space *addr_space,
> + struct vfio_pfn *old)
> +{
> + rb_erase(&old->node, &addr_space->pfn_list);
> +}
> +
> +static int vfio_add_to_pfn_list(struct vfio_addr_space *addr_space,
> + unsigned long pfn, int prot)
> +{
> + struct vfio_pfn *vpfn;
> +
> + vpfn = kzalloc(sizeof(*vpfn), GFP_KERNEL);
> + if (!vpfn)
> + return -ENOMEM;
> +
> + vpfn->pfn = pfn;
> + vpfn->prot = prot;
> + atomic_set(&vpfn->ref_count, 1);
> + vfio_link_pfn(addr_space, vpfn);
> + return 0;
> +}
> +
> +static void vfio_remove_from_pfn_list(struct vfio_addr_space *addr_space,
> + struct vfio_pfn *vpfn)
> +{
> + vfio_unlink_pfn(addr_space, vpfn);
> + kfree(vpfn);
> +}
> +
> +static int vfio_pfn_account(struct vfio_addr_space *addr_space,
> + unsigned long pfn)
> +{
> + struct vfio_pfn *p;
> + int ret = 1;
> +
> + mutex_lock(&addr_space->pfn_list_lock);
> + p = vfio_find_pfn(addr_space, pfn);
> + if (p)
> + ret = 0;
> + mutex_unlock(&addr_space->pfn_list_lock);
> + return ret;
> +}
> +
> struct vwork {
> struct mm_struct *mm;
> long npage;
> @@ -304,16 +410,18 @@ static long __vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
> unsigned long limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> bool lock_cap = dma->mlock_cap;
> struct mm_struct *mm = dma->addr_space->mm;
> - long ret, i;
> + long ret, i, lock_acct;
> bool rsvd;
>
> ret = vaddr_get_pfn(mm, vaddr, prot, pfn_base);
> if (ret)
> return ret;
>
> + lock_acct = vfio_pfn_account(dma->addr_space, *pfn_base);
> +
> rsvd = is_invalid_reserved_pfn(*pfn_base);
>
> - if (!rsvd && !lock_cap && mm->locked_vm + 1 > limit) {
> + if (!rsvd && !lock_cap && mm->locked_vm + lock_acct > limit) {
> put_pfn(*pfn_base, prot);
> pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__,
> limit << PAGE_SHIFT);
> @@ -340,8 +448,10 @@ static long __vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
> break;
> }
>
> + lock_acct += vfio_pfn_account(dma->addr_space, pfn);
> +
> if (!rsvd && !lock_cap &&
> - mm->locked_vm + i + 1 > limit) {
> + mm->locked_vm + lock_acct + 1 > limit) {
> put_pfn(pfn, prot);
> pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n",
> __func__, limit << PAGE_SHIFT);
> @@ -350,7 +460,7 @@ static long __vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
> }
>
> if (!rsvd)
> - vfio_lock_acct(mm, i);
> + vfio_lock_acct(mm, lock_acct);
>
> return i;
> }
> @@ -370,14 +480,214 @@ static long __vfio_unpin_pages_remote(struct vfio_dma *dma, unsigned long pfn,
> return unlocked;
> }
>
> -static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma)
> +static int __vfio_pin_page_external(struct vfio_dma *dma, unsigned long vaddr,
> + int prot, unsigned long *pfn_base,
> + bool do_accounting)
> +{
> + struct task_struct *task = dma->task;
> + unsigned long limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> + bool lock_cap = dma->mlock_cap;
> + struct mm_struct *mm = dma->addr_space->mm;
> + int ret;
> + bool rsvd;
> +
> + ret = vaddr_get_pfn(mm, vaddr, prot, pfn_base);
> + if (ret)
> + return ret;
> +
> + rsvd = is_invalid_reserved_pfn(*pfn_base);
> +
> + if (!rsvd && !lock_cap && mm->locked_vm + 1 > limit) {
> + put_pfn(*pfn_base, prot);
> + pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK (%ld) exceeded\n",
> + __func__, task->comm, task_pid_nr(task),
> + limit << PAGE_SHIFT);
> + return -ENOMEM;
> + }
> +
> + if (!rsvd && do_accounting)
> + vfio_lock_acct(mm, 1);
> +
> + return 1;
> +}
> +
> +static void __vfio_unpin_page_external(struct vfio_addr_space *addr_space,
> + unsigned long pfn, int prot,
> + bool do_accounting)
> +{
> + put_pfn(pfn, prot);
> +
> + if (do_accounting)
> + vfio_lock_acct(addr_space->mm, -1);
Can't we batch this like we do elsewhere? Intel folks, AIUI you intend
to pin all VM memory through this side channel, have you tested the
scalability and performance of this with larger VMs? Our vfio_pfn
data structure alone is 40 bytes per pinned page, which means for
each 1GB of VM memory, we have 10MBs worth of struct vfio_pfn!
Additionally, unmapping each 1GB of VM memory will result in 256k
separate vfio_lock_acct() callbacks. I'm concerned that we're not
being efficient enough in either space or time.
One thought might be whether we really need to save the pfn, we better
always get the same result if we pin it again, or maybe we can just do
a lookup through the mm at that point without re-pinning. Could we get
to the point where we only need an atomic_t ref count per page in a
linear array relative to the IOVA? That would give us 1MB per 1GB
overhead. The semantics of the pin and unpin would make more sense then
too, both would take an IOVA range, only pinning would need a return
mechanism. For instance:
int pin_pages(void *iommu_data, dma_addr_t iova_base,
int npage, unsigned long *pfn_base);
This would pin physically contiguous pages up to npage, returning the
base pfn and returning the number of pages pinned (<= npage). The
vendor driver would make multiple calls to fill the necessary range.
Unpin would then simply be:
void unpin_pages(void *iommu_data, dma_addr_t iova_base, int npage);
Hugepage usage would really make such an interface shine (ie. 2MB+
contiguous ranges). A downside would be the overhead of getting the
group and container reference in vfio for each callback, perhaps we'd
need to figure out how the vendor driver could hold that reference.
The current API of passing around pfn arrays, further increasing the
overhead of the whole ecosystem just makes me cringe though.
> +}
> +
> +static int vfio_unpin_pfn(struct vfio_addr_space *addr_space,
> + struct vfio_pfn *vpfn, bool do_accounting)
> +{
> + __vfio_unpin_page_external(addr_space, vpfn->pfn, vpfn->prot,
> + do_accounting);
> +
> + if (atomic_dec_and_test(&vpfn->ref_count))
> + vfio_remove_from_pfn_list(addr_space, vpfn);
> +
> + return 1;
> +}
> +
> +static int vfio_iommu_type1_pin_pages(void *iommu_data,
> + unsigned long *user_pfn,
> + int npage, int prot,
> + unsigned long *phys_pfn)
> +{
> + struct vfio_iommu *iommu = iommu_data;
> + int i, j, ret;
> + unsigned long remote_vaddr;
> + unsigned long *pfn = phys_pfn;
> + struct vfio_dma *dma;
> + bool do_accounting;
> +
> + if (!iommu || !user_pfn || !phys_pfn)
> + return -EINVAL;
> +
> + mutex_lock(&iommu->lock);
> +
> + if (!iommu->external_domain) {
> + ret = -EINVAL;
> + goto pin_done;
> + }
> +
> + /*
> + * If iommu capable domain exist in the container then all pages are
> + * already pinned and accounted. Accouting should be done if there is no
> + * iommu capable domain in the container.
> + */
> + do_accounting = !IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu);
> +
> + for (i = 0; i < npage; i++) {
> + struct vfio_pfn *p;
> + dma_addr_t iova;
> +
> + iova = user_pfn[i] << PAGE_SHIFT;
> +
> + dma = vfio_find_dma(iommu, iova, 0);
> + if (!dma) {
> + ret = -EINVAL;
> + goto pin_unwind;
> + }
> +
> + remote_vaddr = dma->vaddr + iova - dma->iova;
> +
> + ret = __vfio_pin_page_external(dma, remote_vaddr, prot,
> + &pfn[i], do_accounting);
Please wrap such that the following line falls within the relevant ()s
when possible. Above and below on unpin calls.
> + if (ret <= 0) {
> + WARN_ON(!ret);
> + goto pin_unwind;
> + }
> +
> + mutex_lock(&dma->addr_space->pfn_list_lock);
> +
> + /* search if pfn exist */
> + p = vfio_find_pfn(dma->addr_space, pfn[i]);
> + if (p) {
> + atomic_inc(&p->ref_count);
We never test whether (p->prot == prot), shouldn't we be doing
something in that case? In fact, why do we allow the side-channel
through the .{un}pin_pages to specify page protection flags that might
be different than the user specified for the DMA_MAP? If the user
specified read-only, the vendor driver should not be allowed to
override with read-write access.
> + mutex_unlock(&dma->addr_space->pfn_list_lock);
> + continue;
> + }
> +
> + ret = vfio_add_to_pfn_list(dma->addr_space, pfn[i], prot);
> + mutex_unlock(&dma->addr_space->pfn_list_lock);
> +
> + if (ret) {
> + __vfio_unpin_page_external(dma->addr_space, pfn[i],
> + prot, do_accounting);
> + goto pin_unwind;
> + }
> + }
> +
> + ret = i;
> + goto pin_done;
> +
> +pin_unwind:
> + pfn[i] = 0;
> + for (j = 0; j < i; j++) {
> + struct vfio_pfn *p;
> + dma_addr_t iova;
> +
> + iova = user_pfn[j] << PAGE_SHIFT;
> +
> + dma = vfio_find_dma(iommu, iova, 0);
> +
> + mutex_lock(&dma->addr_space->pfn_list_lock);
> + p = vfio_find_pfn(dma->addr_space, pfn[j]);
> + if (p)
> + vfio_unpin_pfn(dma->addr_space, p, do_accounting);
> +
> + mutex_unlock(&dma->addr_space->pfn_list_lock);
> + pfn[j] = 0;
> + }
> +
> +pin_done:
> + mutex_unlock(&iommu->lock);
> + return ret;
> +}
> +
> +static int vfio_iommu_type1_unpin_pages(void *iommu_data,
> + unsigned long *user_pfn,
> + unsigned long *pfn,
> + int npage)
> +{
> + struct vfio_iommu *iommu = iommu_data;
> + bool do_accounting;
> + int unlocked = 0, i;
> +
> + if (!iommu || !user_pfn || !pfn)
> + return -EINVAL;
> +
> + mutex_lock(&iommu->lock);
> +
> + if (!iommu->external_domain) {
> + mutex_unlock(&iommu->lock);
> + return -EINVAL;
> + }
> +
> + do_accounting = !IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu);
> +
> + for (i = 0; i < npage; i++) {
> + struct vfio_pfn *p;
> + struct vfio_dma *dma;
> + dma_addr_t iova;
> +
> + iova = user_pfn[i] << PAGE_SHIFT;
> +
> + dma = vfio_find_dma(iommu, iova, 0);
> + if (!dma)
> + goto unpin_exit;
> +
> + mutex_lock(&dma->addr_space->pfn_list_lock);
> + /* verify if pfn exist in pfn_list */
> + p = vfio_find_pfn(dma->addr_space, pfn[i]);
> + if (p)
> + unlocked += vfio_unpin_pfn(dma->addr_space, p,
> + do_accounting);
> + mutex_unlock(&dma->addr_space->pfn_list_lock);
> + }
> +unpin_exit:
> + mutex_unlock(&iommu->lock);
> + return unlocked;
> +}
> +
> +static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
> + bool do_accounting)
> {
> dma_addr_t iova = dma->iova, end = dma->iova + dma->size;
> struct vfio_domain *domain, *d;
> long unlocked = 0;
>
> if (!dma->size)
> - return;
> + return 0;
> +
> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
> + return 0;
> +
> /*
> * We use the IOMMU to track the physical addresses, otherwise we'd
> * need a much more complicated tracking system. Unfortunately that
> @@ -427,12 +737,17 @@ static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma)
> cond_resched();
> }
>
> - vfio_lock_acct(dma->addr_space->mm, -unlocked);
> + dma->iommu_mapped = false;
> + if (do_accounting) {
> + vfio_lock_acct(dma->addr_space->mm, -unlocked);
> + return 0;
> + }
> + return unlocked;
> }
>
> static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
> {
> - vfio_unmap_unpin(iommu, dma);
> + vfio_unmap_unpin(iommu, dma, true);
> vfio_unlink_dma(iommu, dma);
>
> if (atomic_dec_and_test(&dma->addr_space->ref_count)) {
> @@ -642,6 +957,8 @@ static int vfio_pin_map_dma(struct vfio_iommu *iommu, struct vfio_dma *dma,
> dma->size += npage << PAGE_SHIFT;
> }
>
> + dma->iommu_mapped = true;
> +
> if (ret)
> vfio_remove_dma(iommu, dma);
>
> @@ -706,6 +1023,8 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
> goto do_map_err;
> }
> addr_space->mm = mm;
> + addr_space->pfn_list = RB_ROOT;
> + mutex_init(&addr_space->pfn_list_lock);
> atomic_set(&addr_space->ref_count, 1);
> list_add(&addr_space->next, &iommu->addr_space_list);
> free_addr_space_on_err = true;
> @@ -733,7 +1052,11 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
> /* Insert zero-sized and grow as we map chunks of it */
> vfio_link_dma(iommu, dma);
>
> - ret = vfio_pin_map_dma(iommu, dma, size);
> + /* Don't pin and map if container doesn't contain IOMMU capable domain*/
> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
> + dma->size = size;
> + else
> + ret = vfio_pin_map_dma(iommu, dma, size);
> do_map_err:
> mutex_unlock(&iommu->lock);
> return ret;
> @@ -762,10 +1085,6 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
> d = list_first_entry(&iommu->domain_list, struct vfio_domain, next);
> n = rb_first(&iommu->dma_list);
>
> - /* If there's not a domain, there better not be any mappings */
> - if (WARN_ON(n && !d))
> - return -EINVAL;
> -
> for (; n; n = rb_next(n)) {
> struct vfio_dma *dma;
> dma_addr_t iova;
> @@ -774,20 +1093,43 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
> iova = dma->iova;
>
> while (iova < dma->iova + dma->size) {
> - phys_addr_t phys = iommu_iova_to_phys(d->domain, iova);
> + phys_addr_t phys;
> size_t size;
>
> - if (WARN_ON(!phys)) {
> - iova += PAGE_SIZE;
> - continue;
> - }
> + if (dma->iommu_mapped) {
> + phys = iommu_iova_to_phys(d->domain, iova);
> +
> + if (WARN_ON(!phys)) {
> + iova += PAGE_SIZE;
> + continue;
> + }
>
> - size = PAGE_SIZE;
> + size = PAGE_SIZE;
>
> - while (iova + size < dma->iova + dma->size &&
> - phys + size == iommu_iova_to_phys(d->domain,
> + while (iova + size < dma->iova + dma->size &&
> + phys + size == iommu_iova_to_phys(d->domain,
> iova + size))
> - size += PAGE_SIZE;
> + size += PAGE_SIZE;
> + } else {
> + unsigned long pfn;
> + unsigned long vaddr = dma->vaddr +
> + (iova - dma->iova);
> + size_t n = dma->iova + dma->size - iova;
> + long npage;
> +
> + npage = __vfio_pin_pages_remote(dma, vaddr,
> + n >> PAGE_SHIFT,
> + dma->prot,
> + &pfn);
> + if (npage <= 0) {
> + WARN_ON(!npage);
> + ret = (int)npage;
> + return ret;
> + }
> +
> + phys = pfn << PAGE_SHIFT;
> + size = npage << PAGE_SHIFT;
> + }
>
> ret = iommu_map(domain->domain, iova, phys,
> size, dma->prot | domain->prot);
> @@ -796,6 +1138,8 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
>
> iova += size;
> }
> +
> + dma->iommu_mapped = true;
> }
>
> return 0;
> @@ -853,7 +1197,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> struct vfio_iommu *iommu = iommu_data;
> struct vfio_group *group;
> struct vfio_domain *domain, *d;
> - struct bus_type *bus = NULL;
> + struct bus_type *bus = NULL, *mdev_bus;
> int ret;
>
> mutex_lock(&iommu->lock);
> @@ -865,6 +1209,13 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> }
> }
>
> + if (iommu->external_domain) {
> + if (find_iommu_group(iommu->external_domain, iommu_group)) {
> + mutex_unlock(&iommu->lock);
> + return -EINVAL;
> + }
> + }
> +
> group = kzalloc(sizeof(*group), GFP_KERNEL);
> domain = kzalloc(sizeof(*domain), GFP_KERNEL);
> if (!group || !domain) {
> @@ -879,6 +1230,25 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> if (ret)
> goto out_free;
>
> + mdev_bus = symbol_get(mdev_bus_type);
> +
> + if (mdev_bus) {
> + if ((bus == mdev_bus) && !iommu_present(bus)) {
> + symbol_put(mdev_bus_type);
> + if (!iommu->external_domain) {
> + INIT_LIST_HEAD(&domain->group_list);
> + iommu->external_domain = domain;
> + } else
> + kfree(domain);
> +
> + list_add(&group->next,
> + &iommu->external_domain->group_list);
> + mutex_unlock(&iommu->lock);
> + return 0;
> + }
> + symbol_put(mdev_bus_type);
> + }
> +
> domain->domain = iommu_domain_alloc(bus);
> if (!domain->domain) {
> ret = -EIO;
> @@ -969,6 +1339,51 @@ static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
> vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
> }
>
> +static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
> +{
> + struct vfio_addr_space *as;
> +
> + list_for_each_entry(as, &iommu->addr_space_list, next) {
> + struct rb_node *n, *p;
> + long locked = 0, unlocked = 0;
> +
> + n = rb_first(&iommu->dma_list);
> + for (; n; n = rb_next(n)) {
> + struct vfio_dma *dma;
> +
> + dma = rb_entry(n, struct vfio_dma, node);
> + if (dma->addr_space == as)
> + unlocked += vfio_unmap_unpin(iommu, dma, false);
> + }
> +
> + mutex_lock(&as->pfn_list_lock);
> + p = rb_first(&as->pfn_list);
> + for (; p; p = rb_next(p))
> + locked++;
> +
> + mutex_unlock(&as->pfn_list_lock);
> + vfio_lock_acct(as->mm, locked - unlocked);
> + }
> +}
> +
> +static void vfio_external_unpin_all(struct vfio_iommu *iommu,
> + bool do_accounting)
> +{
> + struct vfio_addr_space *as;
> +
> + list_for_each_entry(as, &iommu->addr_space_list, next) {
> + struct rb_node *node;
> +
> + mutex_lock(&as->pfn_list_lock);
> + while ((node = rb_first(&as->pfn_list)))
> + vfio_unpin_pfn(as,
> + rb_entry(node, struct vfio_pfn, node),
> + do_accounting);
> +
> + mutex_unlock(&as->pfn_list_lock);
> + }
> +}
> +
> static void vfio_iommu_type1_detach_group(void *iommu_data,
> struct iommu_group *iommu_group)
> {
> @@ -978,6 +1393,28 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
>
> mutex_lock(&iommu->lock);
>
> + if (iommu->external_domain) {
> + domain = iommu->external_domain;
> + group = find_iommu_group(domain, iommu_group);
> + if (group) {
> + list_del(&group->next);
> + kfree(group);
> +
> + if (list_empty(&domain->group_list)) {
> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) {
> + vfio_external_unpin_all(iommu, true);
> + vfio_iommu_unmap_unpin_all(iommu);
> + } else
> + vfio_external_unpin_all(iommu, false);
> + kfree(domain);
> + iommu->external_domain = NULL;
> + }
> + goto detach_group_done;
> + }
> + }
> +
> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
> + goto detach_group_done;
>
> list_for_each_entry(domain, &iommu->domain_list, next) {
> group = find_iommu_group(domain, iommu_group);
> @@ -988,21 +1425,27 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
> list_del(&group->next);
> kfree(group);
> /*
> - * Group ownership provides privilege, if the group
> - * list is empty, the domain goes away. If it's the
> - * last domain, then all the mappings go away too.
> + * Group ownership provides privilege, if the group list is
> + * empty, the domain goes away. If it's the last domain with
> + * iommu and external domain doesn't exist, then all the
> + * mappings go away too. If it's the last domain with iommu and
> + * external domain exist, update accounting
> */
> if (list_empty(&domain->group_list)) {
> - if (list_is_singular(&iommu->domain_list))
> - vfio_iommu_unmap_unpin_all(iommu);
> + if (list_is_singular(&iommu->domain_list)) {
> + if (!iommu->external_domain)
> + vfio_iommu_unmap_unpin_all(iommu);
> + else
> + vfio_iommu_unmap_unpin_reaccount(iommu);
> + }
> iommu_domain_free(domain->domain);
> list_del(&domain->next);
> kfree(domain);
> }
> - goto done;
> + break;
> }
>
> -done:
> +detach_group_done:
> mutex_unlock(&iommu->lock);
> }
>
> @@ -1028,29 +1471,46 @@ static void *vfio_iommu_type1_open(unsigned long arg)
> }
>
> INIT_LIST_HEAD(&iommu->domain_list);
> + INIT_LIST_HEAD(&iommu->addr_space_list);
> iommu->dma_list = RB_ROOT;
> mutex_init(&iommu->lock);
>
> return iommu;
> }
>
> +static void vfio_release_domain(struct vfio_domain *domain, bool external)
> +{
> + struct vfio_group *group, *group_tmp;
> +
> + list_for_each_entry_safe(group, group_tmp,
> + &domain->group_list, next) {
> + if (!external)
> + iommu_detach_group(domain->domain, group->iommu_group);
> + list_del(&group->next);
> + kfree(group);
> + }
> +
> + if (!external)
> + iommu_domain_free(domain->domain);
> +}
> +
> static void vfio_iommu_type1_release(void *iommu_data)
> {
> struct vfio_iommu *iommu = iommu_data;
> struct vfio_domain *domain, *domain_tmp;
> - struct vfio_group *group, *group_tmp;
> +
> + if (iommu->external_domain) {
> + vfio_release_domain(iommu->external_domain, true);
> + vfio_external_unpin_all(iommu, false);
> + kfree(iommu->external_domain);
> + iommu->external_domain = NULL;
> + }
>
> vfio_iommu_unmap_unpin_all(iommu);
>
> list_for_each_entry_safe(domain, domain_tmp,
> &iommu->domain_list, next) {
> - list_for_each_entry_safe(group, group_tmp,
> - &domain->group_list, next) {
> - iommu_detach_group(domain->domain, group->iommu_group);
> - list_del(&group->next);
> - kfree(group);
> - }
> - iommu_domain_free(domain->domain);
> + vfio_release_domain(domain, false);
> list_del(&domain->next);
> kfree(domain);
> }
> @@ -1158,6 +1618,8 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
> .ioctl = vfio_iommu_type1_ioctl,
> .attach_group = vfio_iommu_type1_attach_group,
> .detach_group = vfio_iommu_type1_detach_group,
> + .pin_pages = vfio_iommu_type1_pin_pages,
> + .unpin_pages = vfio_iommu_type1_unpin_pages,
> };
>
> static int __init vfio_iommu_type1_init(void)
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