[PATCH kernel 6/9] KVM: PPC: Associate IOMMU group with guest view of TCE table
David Gibson
david at gibson.dropbear.id.au
Mon Mar 7 17:25:23 AEDT 2016
On Mon, Mar 07, 2016 at 02:41:14PM +1100, Alexey Kardashevskiy wrote:
> The existing in-kernel TCE table for emulated devices contains
> guest physical addresses which are accesses by emulated devices.
> Since we need to keep this information for VFIO devices too
> in order to implement H_GET_TCE, we are reusing it.
>
> This adds IOMMU group list to kvmppc_spapr_tce_table. Each group
> will have an iommu_table pointer.
>
> This adds kvm_spapr_tce_attach_iommu_group() helper and its detach
> counterpart to manage the lists.
>
> This puts a group when:
> - guest copy of TCE table is destroyed when TCE table fd is closed;
> - kvm_spapr_tce_detach_iommu_group() is called from
> the KVM_DEV_VFIO_GROUP_DEL ioctl handler in the case vfio-pci hotunplug
> (will be added in the following patch).
>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
> arch/powerpc/include/asm/kvm_host.h | 8 +++
> arch/powerpc/include/asm/kvm_ppc.h | 6 ++
> arch/powerpc/kvm/book3s_64_vio.c | 108 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 122 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 2e7c791..2c5c823 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -178,6 +178,13 @@ struct kvmppc_pginfo {
> atomic_t refcnt;
> };
>
> +struct kvmppc_spapr_tce_group {
> + struct list_head next;
> + struct rcu_head rcu;
> + struct iommu_group *refgrp;/* for reference counting only */
> + struct iommu_table *tbl;
> +};
> +
> struct kvmppc_spapr_tce_table {
> struct list_head list;
> struct kvm *kvm;
> @@ -186,6 +193,7 @@ struct kvmppc_spapr_tce_table {
> u32 page_shift;
> u64 offset; /* in pages */
> u64 size; /* window size in pages */
> + struct list_head groups;
> struct page *pages[0];
> };
>
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
> index 2544eda..d1482dc 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -164,6 +164,12 @@ extern void kvmppc_map_vrma(struct kvm_vcpu *vcpu,
> struct kvm_memory_slot *memslot, unsigned long porder);
> extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu);
>
> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm,
> + unsigned long liobn,
> + phys_addr_t start_addr,
> + struct iommu_group *grp);
> +extern void kvm_spapr_tce_detach_iommu_group(struct kvm *kvm,
> + struct iommu_group *grp);
> extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
> struct kvm_create_spapr_tce_64 *args);
> extern struct kvmppc_spapr_tce_table *kvmppc_find_table(
> diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
> index 2c2d103..846d16d 100644
> --- a/arch/powerpc/kvm/book3s_64_vio.c
> +++ b/arch/powerpc/kvm/book3s_64_vio.c
> @@ -27,6 +27,7 @@
> #include <linux/hugetlb.h>
> #include <linux/list.h>
> #include <linux/anon_inodes.h>
> +#include <linux/iommu.h>
>
> #include <asm/tlbflush.h>
> #include <asm/kvm_ppc.h>
> @@ -95,10 +96,18 @@ static void release_spapr_tce_table(struct rcu_head *head)
> struct kvmppc_spapr_tce_table *stt = container_of(head,
> struct kvmppc_spapr_tce_table, rcu);
> unsigned long i, npages = kvmppc_tce_pages(stt->size);
> + struct kvmppc_spapr_tce_group *kg;
>
> for (i = 0; i < npages; i++)
> __free_page(stt->pages[i]);
>
> + while (!list_empty(&stt->groups)) {
> + kg = list_first_entry(&stt->groups,
> + struct kvmppc_spapr_tce_group, next);
> + list_del(&kg->next);
> + kfree(kg);
> + }
> +
> kfree(stt);
> }
>
> @@ -129,9 +138,15 @@ static int kvm_spapr_tce_mmap(struct file *file, struct vm_area_struct *vma)
> static int kvm_spapr_tce_release(struct inode *inode, struct file *filp)
> {
> struct kvmppc_spapr_tce_table *stt = filp->private_data;
> + struct kvmppc_spapr_tce_group *kg;
>
> list_del_rcu(&stt->list);
>
> + list_for_each_entry_rcu(kg, &stt->groups, next) {
> + iommu_group_put(kg->refgrp);
> + kg->refgrp = NULL;
> + }
What's the reason for this kind of two-phase deletion? Dereffing the
group here, and setting to NULL, then actually removing from the liast above.
> kvm_put_kvm(stt->kvm);
>
> kvmppc_account_memlimit(
> @@ -146,6 +161,98 @@ static const struct file_operations kvm_spapr_tce_fops = {
> .release = kvm_spapr_tce_release,
> };
>
> +extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm,
> + unsigned long liobn,
> + phys_addr_t start_addr,
> + struct iommu_group *grp)
> +{
> + struct kvmppc_spapr_tce_table *stt = NULL;
> + struct iommu_table_group *table_group;
> + long i;
> + bool found = false;
> + struct kvmppc_spapr_tce_group *kg;
> + struct iommu_table *tbltmp;
> +
> + /* Check this LIOBN hasn't been previously allocated */
This comment does not appear to be correct.
> + list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {
> + if (stt->liobn == liobn) {
> + if ((stt->offset << stt->page_shift) != start_addr)
> + return -EINVAL;
> +
> + found = true;
> + break;
> + }
> + }
> +
> + if (!found)
> + return -ENODEV;
> +
> + /* Find IOMMU group and table at @start_addr */
> + table_group = iommu_group_get_iommudata(grp);
> + if (!table_group)
> + return -EFAULT;
> +
> + tbltmp = NULL;
> + for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
> + struct iommu_table *tbl = table_group->tables[i];
> +
> + if (!tbl)
> + continue;
> +
> + if ((tbl->it_page_shift == stt->page_shift) &&
> + (tbl->it_offset == stt->offset)) {
> + tbltmp = tbl;
> + break;
> + }
> + }
> + if (!tbltmp)
> + return -ENODEV;
> +
> + list_for_each_entry_rcu(kg, &stt->groups, next) {
> + if (kg->refgrp == grp)
> + return -EBUSY;
> + }
> +
> + kg = kzalloc(sizeof(*kg), GFP_KERNEL);
> + kg->refgrp = grp;
> + kg->tbl = tbltmp;
> + list_add_rcu(&kg->next, &stt->groups);
> +
> + return 0;
> +}
> +
> +static void kvm_spapr_tce_put_group(struct rcu_head *head)
> +{
> + struct kvmppc_spapr_tce_group *kg = container_of(head,
> + struct kvmppc_spapr_tce_group, rcu);
> +
> + iommu_group_put(kg->refgrp);
> + kg->refgrp = NULL;
> + kfree(kg);
> +}
> +
> +extern void kvm_spapr_tce_detach_iommu_group(struct kvm *kvm,
> + struct iommu_group *grp)
Hrm. attach takes an explicit liobn, but this one iterates over all
liobns. Why the asymmetry?
> +{
> + struct kvmppc_spapr_tce_table *stt;
> + struct iommu_table_group *table_group;
> + struct kvmppc_spapr_tce_group *kg;
> +
> + table_group = iommu_group_get_iommudata(grp);
> + if (!table_group)
> + return;
> +
> + list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {
> + list_for_each_entry_rcu(kg, &stt->groups, next) {
> + if (kg->refgrp == grp) {
> + list_del_rcu(&kg->next);
> + call_rcu(&kg->rcu, kvm_spapr_tce_put_group);
> + break;
> + }
> + }
> + }
> +}
> +
> long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
> struct kvm_create_spapr_tce_64 *args)
> {
> @@ -181,6 +288,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
> stt->offset = args->offset;
> stt->size = size;
> stt->kvm = kvm;
> + INIT_LIST_HEAD_RCU(&stt->groups);
>
> for (i = 0; i < npages; i++) {
> stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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