Hi Zenghui,
On 4/7/21 9:39 AM, Zenghui Yu wrote:
> Hi Eric,
>
> On 2021/2/24 4:56, 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.
>>
>> Nested mode is not compatible with HW MSI regions as in that
>> case gDB and hDB should have a 1-1 mapping. This check will
>> be done when attaching each device to the IOMMU domain.
>>
>> Signed-off-by: Eric Auger
>
> [...]
>
>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>> index f659395e7959..d25eb7cecaa7 100644
>> --- a/drivers/iommu/dma-iommu.c
>> +++ b/drivers/iommu/dma-iommu.c
>> @@ -19,6 +19,7 @@
>> #include
>> #include
>> #include
>> +#include
>
> Duplicated include.
sure
>
>> #include
>> #include
>> #include
>> @@ -29,12 +30,15 @@
>> 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 {
>> @@ -46,6 +50,7 @@ struct iommu_dma_cookie {
>> dma_addr_t msi_iova;
>
> msi_iova is unused in the nested mode, but we still set it to the start
> address of the RESV_SW_MSI region (in iommu_get_msi_cookie()), which
> looks a bit strange to me.
I agree with you
>
>> };
>> struct list_head msi_page_list;
>> + spinlock_t msi_lock;
>
> Should msi_lock be grabbed everywhere msi_page_list is populated?
> Especially in iommu_dma_get_msi_page(), which can be invoked from the
> irqchip driver.
Yes I agree
>
>> /* Domain for flush queue callback; NULL if flush queue not in
>> use */
>> struct iommu_domain *fq_domain;
>> @@ -87,6 +92,7 @@ static struct iommu_dma_cookie *cookie_alloc(enum
>> iommu_dma_cookie_type type)
>> cookie = kzalloc(sizeof(*cookie), GFP_KERNEL);
>> if (cookie) {
>> + spin_lock_init(&cookie->msi_lock);
>> INIT_LIST_HEAD(&cookie->msi_page_list);
>> cookie->type = type;
>> }
>> @@ -120,14 +126,17 @@ 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
>
> s/iommu_dma_bind_doorbell/iommu_dma_bind_guest_msi/ ?
correct
>
>> + * 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;
>> @@ -135,7 +144,12 @@ 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);
>
> Redundant space.
yep
>
>> + if (!ret && nesting)
>> + cookie = cookie_alloc(IOMMU_DMA_NESTED_MSI_COOKIE);
>> + else
>> + cookie = cookie_alloc(IOMMU_DMA_MSI_COOKIE);
>> +
>> if (!cookie)
>> return -ENOMEM;
>> @@ -156,6 +170,7 @@ 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;