The underlying host may be limiting the number of outstanding DMA
requests for type 1 IOMMU. Add helper functions to check for the
DMA available capability and retrieve the current number of DMA
mappings allowed.
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++
include/hw/vfio/vfio-common.h | 2 ++
2 files changed, 39 insertions(+)
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 3335714..7f4a338 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -844,6 +844,43 @@ vfio_get_region_info_cap(struct vfio_region_info *info, uint16_t id)
return NULL;
}
+static struct vfio_info_cap_header *
+vfio_get_iommu_type1_info_cap(struct vfio_iommu_type1_info *info, uint16_t id)
+{
+ struct vfio_info_cap_header *hdr;
+ void *ptr = info;
+
+ if (!(info->flags & VFIO_IOMMU_INFO_CAPS)) {
+ return NULL;
+ }
+
+ for (hdr = ptr + info->cap_offset; hdr != ptr; hdr = ptr + hdr->next) {
+ if (hdr->id == id) {
+ return hdr;
+ }
+ }
+
+ return NULL;
+}
+
+bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
+ unsigned int *avail)
+{
+ struct vfio_info_cap_header *hdr;
+ struct vfio_iommu_type1_info_dma_avail *cap;
+
+ /* If the capability cannot be found, assume no DMA limiting */
+ hdr = vfio_get_iommu_type1_info_cap(info,
+ VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
+ if (hdr == NULL || avail == NULL) {
+ return false;
+ }
+
+ cap = (void *) hdr;
+ *avail = cap->avail;
+ return true;
+}
+
static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
struct vfio_region_info *info)
{
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index c78f3ff..661a380 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -178,6 +178,8 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, Error **errp);
void vfio_put_group(VFIOGroup *group);
int vfio_get_device(VFIOGroup *group, const char *name,
VFIODevice *vbasedev, Error **errp);
+bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
+ unsigned int *avail);
extern const MemoryRegionOps vfio_region_ops;
typedef QLIST_HEAD(VFIOGroupList, VFIOGroup) VFIOGroupList;
--
1.8.3.1
Hi Matthew,
On 9/15/20 12:29 AM, Matthew Rosato wrote:
> The underlying host may be limiting the number of outstanding DMA
> requests for type 1 IOMMU. Add helper functions to check for the
> DMA available capability and retrieve the current number of DMA
> mappings allowed.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
> hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++
> include/hw/vfio/vfio-common.h | 2 ++
> 2 files changed, 39 insertions(+)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 3335714..7f4a338 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -844,6 +844,43 @@ vfio_get_region_info_cap(struct vfio_region_info *info, uint16_t id)
> return NULL;
> }
>
> +static struct vfio_info_cap_header *
> +vfio_get_iommu_type1_info_cap(struct vfio_iommu_type1_info *info, uint16_t id)
> +{
> + struct vfio_info_cap_header *hdr;
> + void *ptr = info;
> +
> + if (!(info->flags & VFIO_IOMMU_INFO_CAPS)) {
> + return NULL;
> + }
> +
> + for (hdr = ptr + info->cap_offset; hdr != ptr; hdr = ptr + hdr->next) {
> + if (hdr->id == id) {
> + return hdr;
> + }
> + }
> +
> + return NULL;
> +}
> +
> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
> + unsigned int *avail)
> +{
> + struct vfio_info_cap_header *hdr;
> + struct vfio_iommu_type1_info_dma_avail *cap;
> +
> + /* If the capability cannot be found, assume no DMA limiting */
> + hdr = vfio_get_iommu_type1_info_cap(info,
> + VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
> + if (hdr == NULL || avail == NULL) {
If you expect the caller to use avail=NULL, then why
return false when there is available information?
> + return false;
> + }
> +
> + cap = (void *) hdr;
> + *avail = cap->avail;
> + return true;
> +}
> +
> static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
> struct vfio_region_info *info)
> {
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index c78f3ff..661a380 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -178,6 +178,8 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, Error **errp);
> void vfio_put_group(VFIOGroup *group);
> int vfio_get_device(VFIOGroup *group, const char *name,
> VFIODevice *vbasedev, Error **errp);
> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
> + unsigned int *avail);
>
> extern const MemoryRegionOps vfio_region_ops;
> typedef QLIST_HEAD(VFIOGroupList, VFIOGroup) VFIOGroupList;
>
On Tue, 15 Sep 2020 08:14:24 +0200
Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
> Hi Matthew,
>
> On 9/15/20 12:29 AM, Matthew Rosato wrote:
> > The underlying host may be limiting the number of outstanding DMA
> > requests for type 1 IOMMU. Add helper functions to check for the
> > DMA available capability and retrieve the current number of DMA
> > mappings allowed.
> >
> > Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> > ---
> > hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++
> > include/hw/vfio/vfio-common.h | 2 ++
> > 2 files changed, 39 insertions(+)
(...)
> > +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
> > + unsigned int *avail)
> > +{
> > + struct vfio_info_cap_header *hdr;
> > + struct vfio_iommu_type1_info_dma_avail *cap;
> > +
> > + /* If the capability cannot be found, assume no DMA limiting */
> > + hdr = vfio_get_iommu_type1_info_cap(info,
> > + VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
> > + if (hdr == NULL || avail == NULL) {
>
> If you expect the caller to use avail=NULL, then why
> return false when there is available information?
I agree; if the purpose of this function is to check if limiting is in
place and only optionally return the actual limit, we should return
true for hdr != NULL and avail == NULL.
>
> > + return false;
> > + }
> > +
> > + cap = (void *) hdr;
> > + *avail = cap->avail;
> > + return true;
> > +}
> > +
> > static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
> > struct vfio_region_info *info)
> > {
(...)
On 9/15/20 2:14 AM, Philippe Mathieu-Daudé wrote:
> Hi Matthew,
>
> On 9/15/20 12:29 AM, Matthew Rosato wrote:
>> The underlying host may be limiting the number of outstanding DMA
>> requests for type 1 IOMMU. Add helper functions to check for the
>> DMA available capability and retrieve the current number of DMA
>> mappings allowed.
>>
>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
>> ---
>> hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++
>> include/hw/vfio/vfio-common.h | 2 ++
>> 2 files changed, 39 insertions(+)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 3335714..7f4a338 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -844,6 +844,43 @@ vfio_get_region_info_cap(struct vfio_region_info *info, uint16_t id)
>> return NULL;
>> }
>>
>> +static struct vfio_info_cap_header *
>> +vfio_get_iommu_type1_info_cap(struct vfio_iommu_type1_info *info, uint16_t id)
>> +{
>> + struct vfio_info_cap_header *hdr;
>> + void *ptr = info;
>> +
>> + if (!(info->flags & VFIO_IOMMU_INFO_CAPS)) {
>> + return NULL;
>> + }
>> +
>> + for (hdr = ptr + info->cap_offset; hdr != ptr; hdr = ptr + hdr->next) {
>> + if (hdr->id == id) {
>> + return hdr;
>> + }
>> + }
>> +
>> + return NULL;
>> +}
>> +
>> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
>> + unsigned int *avail)
>> +{
>> + struct vfio_info_cap_header *hdr;
>> + struct vfio_iommu_type1_info_dma_avail *cap;
>> +
>> + /* If the capability cannot be found, assume no DMA limiting */
>> + hdr = vfio_get_iommu_type1_info_cap(info,
>> + VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
>> + if (hdr == NULL || avail == NULL) {
>
> If you expect the caller to use avail=NULL, then why
> return false when there is available information?
I was not expecting the caller to use avail=NULL as there would be
nowhere to stash the dma_avail count. But you're right, we can at least
still know that the capability is enabled/disabled when avail=NULL.
I can change this by returning true/false solely based upon the
existence of the capability (whether or not hdr==NULL) while only
updating the caller's *avail value when avail!=NULL.
If that's no good, then the alternative would be an assert()
>
>> + return false;
>> + }
>> +
>> + cap = (void *) hdr;
>> + *avail = cap->avail;
>> + return true;
>> +}
>> +
>> static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
>> struct vfio_region_info *info)
>> {
>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
>> index c78f3ff..661a380 100644
>> --- a/include/hw/vfio/vfio-common.h
>> +++ b/include/hw/vfio/vfio-common.h
>> @@ -178,6 +178,8 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, Error **errp);
>> void vfio_put_group(VFIOGroup *group);
>> int vfio_get_device(VFIOGroup *group, const char *name,
>> VFIODevice *vbasedev, Error **errp);
>> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
>> + unsigned int *avail);
>>
>> extern const MemoryRegionOps vfio_region_ops;
>> typedef QLIST_HEAD(VFIOGroupList, VFIOGroup) VFIOGroupList;
>>
>
On Mon, 14 Sep 2020 18:29:28 -0400
Matthew Rosato <mjrosato@linux.ibm.com> wrote:
> The underlying host may be limiting the number of outstanding DMA
> requests for type 1 IOMMU. Add helper functions to check for the
> DMA available capability and retrieve the current number of DMA
> mappings allowed.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
> hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++
> include/hw/vfio/vfio-common.h | 2 ++
> 2 files changed, 39 insertions(+)
>
(...)
> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
> + unsigned int *avail)
> +{
> + struct vfio_info_cap_header *hdr;
> + struct vfio_iommu_type1_info_dma_avail *cap;
> +
> + /* If the capability cannot be found, assume no DMA limiting */
> + hdr = vfio_get_iommu_type1_info_cap(info,
> + VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
...don't you need a headers sync first to get the new definitions?
(...)
On 9/15/20 6:33 AM, Cornelia Huck wrote:
> On Mon, 14 Sep 2020 18:29:28 -0400
> Matthew Rosato <mjrosato@linux.ibm.com> wrote:
>
>> The underlying host may be limiting the number of outstanding DMA
>> requests for type 1 IOMMU. Add helper functions to check for the
>> DMA available capability and retrieve the current number of DMA
>> mappings allowed.
>>
>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
>> ---
>> hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++
>> include/hw/vfio/vfio-common.h | 2 ++
>> 2 files changed, 39 insertions(+)
>>
>
> (...)
>
>> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
>> + unsigned int *avail)
>> +{
>> + struct vfio_info_cap_header *hdr;
>> + struct vfio_iommu_type1_info_dma_avail *cap;
>> +
>> + /* If the capability cannot be found, assume no DMA limiting */
>> + hdr = vfio_get_iommu_type1_info_cap(info,
>> + VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
>
> ...don't you need a headers sync first to get the new definitions?
>
You are right of course, though the associated header change is not yet
merged in the kernel so it's a bit flaky. But bottom line: yes, we
need a header sync first, I'll include one in v3.
> (...)
>
On Tue, 15 Sep 2020 09:57:03 -0400
Matthew Rosato <mjrosato@linux.ibm.com> wrote:
> On 9/15/20 6:33 AM, Cornelia Huck wrote:
> > On Mon, 14 Sep 2020 18:29:28 -0400
> > Matthew Rosato <mjrosato@linux.ibm.com> wrote:
> >
> >> The underlying host may be limiting the number of outstanding DMA
> >> requests for type 1 IOMMU. Add helper functions to check for the
> >> DMA available capability and retrieve the current number of DMA
> >> mappings allowed.
> >>
> >> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> >> ---
> >> hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++
> >> include/hw/vfio/vfio-common.h | 2 ++
> >> 2 files changed, 39 insertions(+)
> >>
> >
> > (...)
> >
> >> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
> >> + unsigned int *avail)
> >> +{
> >> + struct vfio_info_cap_header *hdr;
> >> + struct vfio_iommu_type1_info_dma_avail *cap;
> >> +
> >> + /* If the capability cannot be found, assume no DMA limiting */
> >> + hdr = vfio_get_iommu_type1_info_cap(info,
> >> + VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
> >
> > ...don't you need a headers sync first to get the new definitions?
> >
>
> You are right of course, though the associated header change is not yet
> merged in the kernel so it's a bit flaky. But bottom line: yes, we
> need a header sync first, I'll include one in v3.
Just include a placeholder patch :) It's easy to replace them with a
real update prior to merging.
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