Messages in this thread | | | Subject | Re: [PATCH v7 15/23] dma-iommu: Implement NESTED_MSI cookie | From | Robin Murphy <> | Date | Wed, 8 May 2019 17:42:33 +0100 |
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On 08/04/2019 13:19, Eric Auger wrote: > Up to now, when the type was UNMANAGED, we used to > allocate IOVA pages within a reserved IOVA MSI range. > > If both the host and the guest are exposed with SMMUs, each > would allocate an IOVA. The guest allocates an IOVA (gIOVA) > to map onto the guest MSI doorbell (gDB). The Host allocates > another IOVA (hIOVA) to map onto the physical doorbell (hDB). > > So we end up with 2 unrelated mappings, at S1 and S2: > S1 S2 > gIOVA -> gDB > hIOVA -> hDB > > The PCI device would be programmed with hIOVA. > No stage 1 mapping would existing, causing the MSIs to fault. > > iommu_dma_bind_guest_msi() allows to pass gIOVA/gDB > to the host so that gIOVA can be used by the host instead of > re-allocating a new hIOVA. > > S1 S2 > gIOVA -> gDB -> hDB > > this time, the PCI device can be programmed with the gIOVA MSI > doorbell which is correctly mapped through both stages.
Hmm, this implies that both the guest kernel and host userspace are totally broken if hDB is a hardware MSI region...
Robin.
> Signed-off-by: Eric Auger <eric.auger@redhat.com> > > --- > v6 -> v7: > - removed device handle > > v3 -> v4: > - change function names; add unregister > - protect with msi_lock > > v2 -> v3: > - also store the device handle on S1 mapping registration. > This garantees we associate the associated S2 mapping binds > to the correct physical MSI controller. > > v1 -> v2: > - unmap stage2 on put() > --- > drivers/iommu/dma-iommu.c | 129 +++++++++++++++++++++++++++++++++++++- > include/linux/dma-iommu.h | 17 +++++ > 2 files changed, 143 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index 77aabe637a60..9905260ad342 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -35,12 +35,15 @@ > struct iommu_dma_msi_page { > struct list_head list; > dma_addr_t iova; > + dma_addr_t gpa; > phys_addr_t phys; > + size_t s1_granule; > }; > > enum iommu_dma_cookie_type { > IOMMU_DMA_IOVA_COOKIE, > IOMMU_DMA_MSI_COOKIE, > + IOMMU_DMA_NESTED_MSI_COOKIE, > }; > > struct iommu_dma_cookie { > @@ -110,14 +113,17 @@ EXPORT_SYMBOL(iommu_get_dma_cookie); > * > * Users who manage their own IOVA allocation and do not want DMA API support, > * but would still like to take advantage of automatic MSI remapping, can use > - * this to initialise their own domain appropriately. Users should reserve a > + * this to initialise their own domain appropriately. Users may reserve a > * contiguous IOVA region, starting at @base, large enough to accommodate the > * number of PAGE_SIZE mappings necessary to cover every MSI doorbell address > - * used by the devices attached to @domain. > + * used by the devices attached to @domain. The other way round is to provide > + * usable iova pages through the iommu_dma_bind_doorbell API (nested stages > + * use case) > */ > int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base) > { > struct iommu_dma_cookie *cookie; > + int nesting, ret; > > if (domain->type != IOMMU_DOMAIN_UNMANAGED) > return -EINVAL; > @@ -125,7 +131,12 @@ int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base) > if (domain->iova_cookie) > return -EEXIST; > > - cookie = cookie_alloc(IOMMU_DMA_MSI_COOKIE); > + ret = iommu_domain_get_attr(domain, DOMAIN_ATTR_NESTING, &nesting); > + if (!ret && nesting) > + cookie = cookie_alloc(IOMMU_DMA_NESTED_MSI_COOKIE); > + else > + cookie = cookie_alloc(IOMMU_DMA_MSI_COOKIE); > + > if (!cookie) > return -ENOMEM; > > @@ -146,6 +157,7 @@ void iommu_put_dma_cookie(struct iommu_domain *domain) > { > struct iommu_dma_cookie *cookie = domain->iova_cookie; > struct iommu_dma_msi_page *msi, *tmp; > + bool s2_unmap = false; > > if (!cookie) > return; > @@ -153,7 +165,15 @@ void iommu_put_dma_cookie(struct iommu_domain *domain) > if (cookie->type == IOMMU_DMA_IOVA_COOKIE && cookie->iovad.granule) > put_iova_domain(&cookie->iovad); > > + if (cookie->type == IOMMU_DMA_NESTED_MSI_COOKIE) > + s2_unmap = true; > + > list_for_each_entry_safe(msi, tmp, &cookie->msi_page_list, list) { > + if (s2_unmap && msi->phys) { > + size_t size = cookie_msi_granule(cookie); > + > + WARN_ON(iommu_unmap(domain, msi->gpa, size) != size); > + } > list_del(&msi->list); > kfree(msi); > } > @@ -162,6 +182,82 @@ void iommu_put_dma_cookie(struct iommu_domain *domain) > } > EXPORT_SYMBOL(iommu_put_dma_cookie); > > +/** > + * iommu_dma_bind_guest_msi - Allows to pass the stage 1 > + * binding of a virtual MSI doorbell used by @dev. > + * > + * @domain: domain handle > + * @iova: guest iova > + * @gpa: gpa of the virtual doorbell > + * @size: size of the granule used for the stage1 mapping > + * > + * In nested stage use case, the user can provide IOVA/IPA bindings > + * corresponding to a guest MSI stage 1 mapping. When the host needs > + * to map its own MSI doorbells, it can use @gpa as stage 2 input > + * and map it onto the physical MSI doorbell. > + */ > +int iommu_dma_bind_guest_msi(struct iommu_domain *domain, > + dma_addr_t iova, phys_addr_t gpa, size_t size) > +{ > + struct iommu_dma_cookie *cookie = domain->iova_cookie; > + struct iommu_dma_msi_page *msi; > + int ret = 0; > + > + if (!cookie) > + return -EINVAL; > + > + if (cookie->type != IOMMU_DMA_NESTED_MSI_COOKIE) > + return -EINVAL; > + > + iova = iova & ~(dma_addr_t)(size - 1); > + gpa = gpa & ~(phys_addr_t)(size - 1); > + > + spin_lock(&cookie->msi_lock); > + > + list_for_each_entry(msi, &cookie->msi_page_list, list) { > + if (msi->iova == iova) > + goto unlock; /* this page is already registered */ > + } > + > + msi = kzalloc(sizeof(*msi), GFP_ATOMIC); > + if (!msi) { > + ret = -ENOMEM; > + goto unlock; > + } > + > + msi->iova = iova; > + msi->gpa = gpa; > + msi->s1_granule = size; > + list_add(&msi->list, &cookie->msi_page_list); > +unlock: > + spin_unlock(&cookie->msi_lock); > + return ret; > +} > +EXPORT_SYMBOL(iommu_dma_bind_guest_msi); > + > +void iommu_dma_unbind_guest_msi(struct iommu_domain *domain, dma_addr_t giova) > +{ > + struct iommu_dma_cookie *cookie = domain->iova_cookie; > + struct iommu_dma_msi_page *msi, *tmp; > + > + list_for_each_entry_safe(msi, tmp, &cookie->msi_page_list, list) { > + dma_addr_t aligned_giova = > + giova & ~(dma_addr_t)(msi->s1_granule - 1); > + > + if (msi->iova == aligned_giova) { > + if (msi->phys) { > + /* unmap the stage 2 */ > + size_t size = cookie_msi_granule(cookie); > + > + WARN_ON(iommu_unmap(domain, msi->gpa, size) != size); > + } > + list_del(&msi->list); > + kfree(msi); > + } > + } > +} > +EXPORT_SYMBOL(iommu_dma_unbind_guest_msi); > + > /** > * iommu_dma_get_resv_regions - Reserved region driver helper > * @dev: Device from iommu_get_resv_regions() > @@ -869,6 +965,33 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev, > if (msi_page->phys == msi_addr) > return msi_page; > > + /* > + * In nested stage mode, we do not allocate an MSI page in > + * a range provided by the user. Instead, IOVA/IPA bindings are > + * individually provided. We reuse thise IOVAs to build the > + * GIOVA -> GPA -> MSI HPA nested stage mapping. > + */ > + if (cookie->type == IOMMU_DMA_NESTED_MSI_COOKIE) { > + list_for_each_entry(msi_page, &cookie->msi_page_list, list) > + if (!msi_page->phys) { > + int ret; > + > + /* do the stage 2 mapping */ > + ret = iommu_map(domain, > + msi_page->gpa, msi_addr, size, > + IOMMU_MMIO | IOMMU_WRITE); > + if (ret) { > + pr_warn("MSI S2 mapping failed (%d)\n", > + ret); > + return NULL; > + } > + msi_page->phys = msi_addr; > + return msi_page; > + } > + pr_warn("%s no MSI binding found\n", __func__); > + return NULL; > + } > + > msi_page = kzalloc(sizeof(*msi_page), GFP_ATOMIC); > if (!msi_page) > return NULL; > diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h > index e760dc5d1fa8..fa898d514edb 100644 > --- a/include/linux/dma-iommu.h > +++ b/include/linux/dma-iommu.h > @@ -24,6 +24,7 @@ > #include <linux/dma-mapping.h> > #include <linux/iommu.h> > #include <linux/msi.h> > +#include <uapi/linux/iommu.h> > > int iommu_dma_init(void); > > @@ -73,6 +74,9 @@ void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle, > /* The DMA API isn't _quite_ the whole story, though... */ > void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg); > void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list); > +int iommu_dma_bind_guest_msi(struct iommu_domain *domain, > + dma_addr_t iova, phys_addr_t gpa, size_t size); > +void iommu_dma_unbind_guest_msi(struct iommu_domain *domain, dma_addr_t giova); > > #else > > @@ -103,6 +107,19 @@ static inline void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg) > { > } > > +static inline int > +iommu_dma_bind_guest_msi(struct iommu_domain *domain, struct device *dev, > + dma_addr_t iova, phys_addr_t gpa, size_t size) > +{ > + return -ENODEV; > +} > + > +static inline void > +iommu_dma_unbind_guest_msi(struct iommu_domain *domain, > + struct device *dev, dma_addr_t giova); > +{ > +} > + > static inline void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list) > { > } >
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