[v7,1/8] genirq/msi: Add a new MSI_FLAG_IRQ_REMAPPING flag

Message ID 1461085990-2547-2-git-send-email-eric.auger@linaro.org
State Superseded
Headers show

Commit Message

Auger Eric April 19, 2016, 5:13 p.m.
Let's introduce a new msi_domain_info flag value, MSI_FLAG_IRQ_REMAPPING
meant to tell the domain supports IRQ REMAPPING, also known as Interrupt
Translation Service. On Intel HW this IRQ remapping capability is
abstracted on IOMMU side while on ARM it is abstracted on MSI controller
side. This flag will be used to know whether the MSI passthrough is
safe.

Signed-off-by: Eric Auger <eric.auger@linaro.org>


---

v4 -> v5:
- seperate flag introduction from first user addition (ITS)
---
 include/linux/msi.h | 2 ++
 1 file changed, 2 insertions(+)

-- 
1.9.1

Comments

Auger Eric April 22, 2016, 12:25 p.m. | #1
Robin,
On 04/22/2016 01:02 PM, Robin Murphy wrote:
> Hi Eric,

> 

> On 19/04/16 18:13, Eric Auger wrote:

>> Let's introduce a new msi_domain_info flag value, MSI_FLAG_IRQ_REMAPPING

>> meant to tell the domain supports IRQ REMAPPING, also known as Interrupt

>> Translation Service. On Intel HW this IRQ remapping capability is

>> abstracted on IOMMU side while on ARM it is abstracted on MSI controller

>> side. This flag will be used to know whether the MSI passthrough is

>> safe.

> 

> Perhaps a nitpick, but given the earlier confusion about what the IOMMU

> flag actually meant this prompts me to wonder if it's worth adjusting

> the general terminology before we propagate it further. What I think we

> actually care about is that one thing or the other "provides MSI

> isolation" rather than "supports MSI remapping", since the latter is all

> to easy to misinterpret the way we did in the SMMU drivers.


The only concern I have is https://lkml.org/lkml/2016/4/18/283 attempts
to define a PCI bus flag dubbed PCI_BUS_FLAGS_MSI_REMAP combining the
iommu & msi layer info. In that sense x86 people may not be keen of
having different terminaologies. Anyway I will follow the consensus, if any.

Best Regards

Eric


> 

> Robin.

> 

>> Signed-off-by: Eric Auger <eric.auger@linaro.org>

>>

>> ---

>>

>> v4 -> v5:

>> - seperate flag introduction from first user addition (ITS)

>> ---

>>   include/linux/msi.h | 2 ++

>>   1 file changed, 2 insertions(+)

>>

>> diff --git a/include/linux/msi.h b/include/linux/msi.h

>> index 8b425c6..08441b1 100644

>> --- a/include/linux/msi.h

>> +++ b/include/linux/msi.h

>> @@ -270,6 +270,8 @@ enum {

>>       MSI_FLAG_MULTI_PCI_MSI        = (1 << 3),

>>       /* Support PCI MSIX interrupts */

>>       MSI_FLAG_PCI_MSIX        = (1 << 4),

>> +    /* Support MSI IRQ remapping service */

>> +    MSI_FLAG_IRQ_REMAPPING        = (1 << 5),

>>   };

>>

>>   int msi_domain_set_affinity(struct irq_data *data, const struct

>> cpumask *mask,

>>

>

Patch

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 8b425c6..08441b1 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -270,6 +270,8 @@  enum {
 	MSI_FLAG_MULTI_PCI_MSI		= (1 << 3),
 	/* Support PCI MSIX interrupts */
 	MSI_FLAG_PCI_MSIX		= (1 << 4),
+	/* Support MSI IRQ remapping service */
+	MSI_FLAG_IRQ_REMAPPING		= (1 << 5),
 };
 
 int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,