diff mbox series

[v14,08/13] dma-iommu: Implement NESTED_MSI cookie

Message ID 20210223205634.604221-9-eric.auger@redhat.com (mailing list archive)
State New, archived
Headers show
Series SMMUv3 Nested Stage Setup (IOMMU part) | expand

Commit Message

Auger Eric Feb. 23, 2021, 8:56 p.m. UTC
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 <eric.auger@redhat.com>

---

v10 -> v11:
- fix compilation if !CONFIG_IOMMU_DMA

v7 -> v8:
- correct iommu_dma_(un)bind_guest_msi when
  !CONFIG_IOMMU_DMA
- Mentioned nested mode is not compatible with HW MSI regions
  in commit message
- protect with msi_lock on unbind

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 | 142 +++++++++++++++++++++++++++++++++++++-
 include/linux/dma-iommu.h |  16 +++++
 2 files changed, 155 insertions(+), 3 deletions(-)

Comments

Zenghui Yu April 7, 2021, 7:39 a.m. UTC | #1
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 <eric.auger@redhat.com>

[...]

> 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 <linux/irq.h>
>   #include <linux/mm.h>
>   #include <linux/mutex.h>
> +#include <linux/mutex.h>

Duplicated include.

>   #include <linux/pci.h>
>   #include <linux/swiotlb.h>
>   #include <linux/scatterlist.h>
> @@ -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.

>   	};
>   	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.

>   
>   	/* 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/ ?

> + * 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.

> +	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;
>   
>   	if (!cookie)
>   		return;
> @@ -163,7 +178,15 @@ 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) {

I don't think @s2_unmap is necessary. Checking 'cookie->type==NESTED'
directly shouldn't be that expensive.

> +			size_t size = cookie_msi_granule(cookie);
> +
> +			WARN_ON(iommu_unmap(domain, msi->gpa, size) != size);
> +		}
>   		list_del(&msi->list);
>   		kfree(msi);
>   	}
> @@ -172,6 +195,92 @@ 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

Can we change it to 'giova' (to match the unbind side)?

> + * @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;
> +
> +	if (!cookie)
> +		return;
> +
> +	if (cookie->type != IOMMU_DMA_NESTED_MSI_COOKIE)
> +		return;
> +
> +	spin_lock(&cookie->msi_lock);
> +
> +	list_for_each_entry(msi, &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);
> +			break;
> +		}
> +	}
> +	spin_unlock(&cookie->msi_lock);
> +}
> +EXPORT_SYMBOL(iommu_dma_unbind_guest_msi);
> +
>   /**
>    * iommu_dma_get_resv_regions - Reserved region driver helper
>    * @dev: Device from iommu_get_resv_regions()
> @@ -1343,6 +1452,33 @@ 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

s/thise/these/

> +	 * 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,

Shouldn't we make sure that the size of S2 mapping is not less than
s1_granule? Although what we need is actually a 32-bit TRANSLATER
register, we don't know where it is mapped in S1.

> +						IOMMU_MMIO | IOMMU_WRITE);

Is it intentional to drop the IOMMU_NOEXEC flag (from @prot)?

> +				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_KERNEL);
>   	if (!msi_page)
>   		return NULL;


Thanks,
Zenghui
Auger Eric April 10, 2021, 1:34 p.m. UTC | #2
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 <eric.auger@redhat.com>
> 
> [...]
> 
>> 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 <linux/irq.h>
>>   #include <linux/mm.h>
>>   #include <linux/mutex.h>
>> +#include <linux/mutex.h>
> 
> Duplicated include.
sure
> 
>>   #include <linux/pci.h>
>>   #include <linux/swiotlb.h>
>>   #include <linux/scatterlist.h>
>> @@ -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;
>>         if (!cookie)
>>           return;
>> @@ -163,7 +178,15 @@ 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) {
> 
> I don't think @s2_unmap is necessary. Checking 'cookie->type==NESTED'
> directly shouldn't be that expensive.
agreed
> 
>> +            size_t size = cookie_msi_granule(cookie);
>> +
>> +            WARN_ON(iommu_unmap(domain, msi->gpa, size) != size);
>> +        }
>>           list_del(&msi->list);
>>           kfree(msi);
>>       }
>> @@ -172,6 +195,92 @@ 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
> 
> Can we change it to 'giova' (to match the unbind side)?
sure
> 
>> + * @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;
>> +
>> +    if (!cookie)
>> +        return;
>> +
>> +    if (cookie->type != IOMMU_DMA_NESTED_MSI_COOKIE)
>> +        return;
>> +
>> +    spin_lock(&cookie->msi_lock);
>> +
>> +    list_for_each_entry(msi, &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);
>> +            break;
>> +        }
>> +    }
>> +    spin_unlock(&cookie->msi_lock);
>> +}
>> +EXPORT_SYMBOL(iommu_dma_unbind_guest_msi);
>> +
>>   /**
>>    * iommu_dma_get_resv_regions - Reserved region driver helper
>>    * @dev: Device from iommu_get_resv_regions()
>> @@ -1343,6 +1452,33 @@ 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
> 
> s/thise/these/
yep
> 
>> +     * 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,
> 
> Shouldn't we make sure that the size of S2 mapping is not less than
> s1_granule? Although what we need is actually a 32-bit TRANSLATER
> register, we don't know where it is mapped in S1.
The GITS_TRANSLATER is at offset 0x40 of the page. That's what I had in
mind. But indeed the doorbell may belong to another MSI controller with
different layout. So yes that's wort checking.

I will add this check in iommu_dma_bind_guest_msi()

> 
>> +                        IOMMU_MMIO | IOMMU_WRITE);
> 
> Is it intentional to drop the IOMMU_NOEXEC flag (from @prot)?
no restoring it.
> 
>> +                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_KERNEL);
>>       if (!msi_page)
>>           return NULL;
> 
> 
> Thanks,
> Zenghui
> 

Thank you for your careful review!

Best Regards

Eric
diff mbox series

Patch

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 <linux/irq.h>
 #include <linux/mm.h>
 #include <linux/mutex.h>
+#include <linux/mutex.h>
 #include <linux/pci.h>
 #include <linux/swiotlb.h>
 #include <linux/scatterlist.h>
@@ -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;
 	};
 	struct list_head		msi_page_list;
+	spinlock_t			msi_lock;
 
 	/* 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
+ * 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);
+	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;
 
 	if (!cookie)
 		return;
@@ -163,7 +178,15 @@  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);
 	}
@@ -172,6 +195,92 @@  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;
+
+	if (!cookie)
+		return;
+
+	if (cookie->type != IOMMU_DMA_NESTED_MSI_COOKIE)
+		return;
+
+	spin_lock(&cookie->msi_lock);
+
+	list_for_each_entry(msi, &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);
+			break;
+		}
+	}
+	spin_unlock(&cookie->msi_lock);
+}
+EXPORT_SYMBOL(iommu_dma_unbind_guest_msi);
+
 /**
  * iommu_dma_get_resv_regions - Reserved region driver helper
  * @dev: Device from iommu_get_resv_regions()
@@ -1343,6 +1452,33 @@  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_KERNEL);
 	if (!msi_page)
 		return NULL;
diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
index 706b68d1359b..7bd785e68477 100644
--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h
@@ -12,6 +12,7 @@ 
 #include <linux/dma-mapping.h>
 #include <linux/iommu.h>
 #include <linux/msi.h>
+#include <uapi/linux/iommu.h>
 
 /* Domain management interface for IOMMU drivers */
 int iommu_get_dma_cookie(struct iommu_domain *domain);
@@ -36,6 +37,9 @@  void iommu_dma_compose_msi_msg(struct msi_desc *desc,
 			       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);
 
 void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,
 		struct iommu_domain *domain);
@@ -77,6 +81,18 @@  static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc,
 {
 }
 
+static inline int
+iommu_dma_bind_guest_msi(struct iommu_domain *domain,
+			 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, dma_addr_t giova)
+{
+}
+
 static inline void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
 {
 }