diff mbox series

[v1,03/14] iommufd/device: Setup MSI on kernel-managed domains

Message ID 5149b7e711a46e81aea8515676cf0e45608b3afd.1678348754.git.nicolinc@nvidia.com
State New
Headers
Series Add Nested Translation Support for SMMUv3 |

Commit Message

Nicolin Chen March 9, 2023, 10:53 a.m. UTC 
  The IOMMU_RESV_SW_MSI is a kernel-managed domain thing. So, it should be
only setup on a kernel-managed domain only. If the attaching domain is a
user-managed domain, redirect the hwpt to hwpt->parent to do it correctly.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/device.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Eric Auger March 10, 2023, 4:45 p.m. UTC | #1 
Hi Nicolin,

On 3/9/23 11:53, Nicolin Chen wrote:
> The IOMMU_RESV_SW_MSI is a kernel-managed domain thing. So, it should be
> only setup on a kernel-managed domain only. If the attaching domain is a
> user-managed domain, redirect the hwpt to hwpt->parent to do it correctly.
>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/iommufd/device.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> index f95b558f5e95..a3e7d2889164 100644
> --- a/drivers/iommu/iommufd/device.c
> +++ b/drivers/iommu/iommufd/device.c
> @@ -350,7 +350,8 @@ static int iommufd_group_setup_msi(struct iommufd_group *igroup,
>  	 * call iommu_get_msi_cookie() on its behalf. This is necessary to setup
>  	 * the MSI window so iommu_dma_prepare_msi() can install pages into our
>  	 * domain after request_irq(). If it is not done interrupts will not
> -	 * work on this domain.
> +	 * work on this domain. And the msi_cookie should be always set into the
s/And the/The/
> +	 * kernel-managed (parent) domain.
>  	 *
>  	 * FIXME: This is conceptually broken for iommufd since we want to allow
>  	 * userspace to change the domains, eg switch from an identity IOAS to a
> @@ -358,6 +359,8 @@ static int iommufd_group_setup_msi(struct iommufd_group *igroup,
>  	 * matches what the IRQ layer actually expects in a newly created
>  	 * domain.
>  	 */
> +	if (hwpt->parent)
> +		hwpt = hwpt->parent;
I guess there is a garantee the parent hwpt is necessarily a
kernel-managed domain?
Is it that part of the spec that enforces it?
IOMMU_HWPT_ALLOC doc says:
" * A user-managed HWPT will be created from a given parent HWPT via
@pt_id, in
 * which the parent HWPT must be allocated previously via the same ioctl
from a
 * given IOAS.
"
Maybe precise that in the commit msg?

Thanks

Eric
>  	if (sw_msi_start != PHYS_ADDR_MAX && !hwpt->msi_cookie) {
>  		rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start);
>  		if (rc)
Nicolin Chen March 11, 2023, 12:17 a.m. UTC | #2 
On Fri, Mar 10, 2023 at 05:45:20PM +0100, Eric Auger wrote:
> External email: Use caution opening links or attachments
> 
> 
> Hi Nicolin,
> 
> On 3/9/23 11:53, Nicolin Chen wrote:
> > The IOMMU_RESV_SW_MSI is a kernel-managed domain thing. So, it should be
> > only setup on a kernel-managed domain only. If the attaching domain is a
> > user-managed domain, redirect the hwpt to hwpt->parent to do it correctly.
> >
> > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> > ---
> >  drivers/iommu/iommufd/device.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> > index f95b558f5e95..a3e7d2889164 100644
> > --- a/drivers/iommu/iommufd/device.c
> > +++ b/drivers/iommu/iommufd/device.c
> > @@ -350,7 +350,8 @@ static int iommufd_group_setup_msi(struct iommufd_group *igroup,
> >        * call iommu_get_msi_cookie() on its behalf. This is necessary to setup
> >        * the MSI window so iommu_dma_prepare_msi() can install pages into our
> >        * domain after request_irq(). If it is not done interrupts will not
> > -      * work on this domain.
> > +      * work on this domain. And the msi_cookie should be always set into the
> s/And the/The/

OK.

> > +      * kernel-managed (parent) domain.
> >        *
> >        * FIXME: This is conceptually broken for iommufd since we want to allow
> >        * userspace to change the domains, eg switch from an identity IOAS to a
> > @@ -358,6 +359,8 @@ static int iommufd_group_setup_msi(struct iommufd_group *igroup,
> >        * matches what the IRQ layer actually expects in a newly created
> >        * domain.
> >        */
> > +     if (hwpt->parent)
> > +             hwpt = hwpt->parent;
> I guess there is a garantee the parent hwpt is necessarily a
> kernel-managed domain?

Yes. It must be.

> Is it that part of the spec that enforces it?

The hwpt_alloc() function has a sanity to enforce that.

> IOMMU_HWPT_ALLOC doc says:
> " * A user-managed HWPT will be created from a given parent HWPT via
> @pt_id, in
>  * which the parent HWPT must be allocated previously via the same ioctl
> from a
>  * given IOAS.
> "
> Maybe precise that in the commit msg?

There is a paragraph just above that, for kernel-managed HWPT:

455  * A normal HWPT will be created with the mappings from the given IOAS.
456  * The @data_type for its allocation can be set to IOMMU_HWPT_TYPE_DEFAULT, or
457  * another type (being listed below) to specialize a kernel-managed HWPT.

Perhaps we could rephrase "normal HWPT" with "kernel-managed
HWPT", to make it more clear.

Thanks
Nic
diff mbox series

Patch

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index f95b558f5e95..a3e7d2889164 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -350,7 +350,8 @@  static int iommufd_group_setup_msi(struct iommufd_group *igroup,
 	 * call iommu_get_msi_cookie() on its behalf. This is necessary to setup
 	 * the MSI window so iommu_dma_prepare_msi() can install pages into our
 	 * domain after request_irq(). If it is not done interrupts will not
-	 * work on this domain.
+	 * work on this domain. And the msi_cookie should be always set into the
+	 * kernel-managed (parent) domain.
 	 *
 	 * FIXME: This is conceptually broken for iommufd since we want to allow
 	 * userspace to change the domains, eg switch from an identity IOAS to a
@@ -358,6 +359,8 @@  static int iommufd_group_setup_msi(struct iommufd_group *igroup,
 	 * matches what the IRQ layer actually expects in a newly created
 	 * domain.
 	 */
+	if (hwpt->parent)
+		hwpt = hwpt->parent;
 	if (sw_msi_start != PHYS_ADDR_MAX && !hwpt->msi_cookie) {
 		rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start);
 		if (rc)