| Message ID | 20190526161004.25232-6-eric.auger@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | SMMUv3 Nested Stage Setup | expand |
On Sun, 26 May 2019 18:09:40 +0200 Eric Auger <eric.auger@redhat.com> wrote: > From: Jacob Pan <jacob.jun.pan@linux.intel.com> > > When an IO page request is processed outside IOMMU subsystem, response > can be delayed or lost. Add a tunable setup parameter such that user can > choose the timeout for IOMMU to track pending page requests. > > This timeout mechanism is a basic safety net which can be implemented in > conjunction with credit based or device level page response exception > handling. > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> > --- > .../admin-guide/kernel-parameters.txt | 8 +++++ > drivers/iommu/iommu.c | 29 +++++++++++++++++++ > 2 files changed, 37 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 138f6664b2e2..b43f0893d252 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1813,6 +1813,14 @@ > 1 - Bypass the IOMMU for DMA. > unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. > > + iommu.prq_timeout= > + Timeout in seconds to wait for page response > + of a pending page request. > + Format: <integer> > + Default: 10 > + 0 - no timeout tracking > + 1 to 100 - allowed range > + > io7= [HW] IO7 for Marvel based alpha systems > See comment before marvel_specify_io7 in > arch/alpha/kernel/core_marvel.c. > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 13b301cfb10f..64e87d56f471 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -45,6 +45,19 @@ static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA; > #endif > static bool iommu_dma_strict __read_mostly = true; > > +/* > + * Timeout to wait for page response of a pending page request. This is > + * intended as a basic safty net in case a pending page request is not > + * responded for an exceptionally long time. Device may also implement > + * its own protection mechanism against this exception. > + * Units are in jiffies with a range between 1 - 100 seconds equivalent. > + * Default to 10 seconds. > + * Setting 0 means no timeout tracking. > + */ > +#define IOMMU_PAGE_RESPONSE_MAX_TIMEOUT (HZ * 100) > +#define IOMMU_PAGE_RESPONSE_DEF_TIMEOUT (HZ * 10) > +static unsigned long prq_timeout = IOMMU_PAGE_RESPONSE_DEF_TIMEOUT; > + > struct iommu_group { > struct kobject kobj; > struct kobject *devices_kobj; > @@ -157,6 +170,22 @@ static int __init iommu_dma_setup(char *str) > } > early_param("iommu.strict", iommu_dma_setup); > > +static int __init iommu_set_prq_timeout(char *str) > +{ > + unsigned long timeout; > + > + if (!str) > + return -EINVAL; > + timeout = simple_strtoul(str, NULL, 0); > + timeout = timeout * HZ; > + if (timeout > IOMMU_PAGE_RESPONSE_MAX_TIMEOUT) > + return -EINVAL; > + prq_timeout = timeout; > + > + return 0; > +} > +early_param("iommu.prq_timeout", iommu_set_prq_timeout); > + > static ssize_t iommu_group_attr_show(struct kobject *kobj, > struct attribute *__attr, char *buf) > { It doesn't seem to make much sense to include this patch without also including "iommu: handle page response timeout". Was that one lost? Dropped? Lives elsewhere? Thanks, Alex
On 03/06/2019 23:32, Alex Williamson wrote: > It doesn't seem to make much sense to include this patch without also > including "iommu: handle page response timeout". Was that one lost? > Dropped? Lives elsewhere? The first 7 patches come from my sva/api branch, where I had forgotten to add the "handle page response timeout" patch. I added it back, probably after Eric sent this version. But I don't think the patch is ready for upstream, as we still haven't decided how to proceed with timeouts. Patches 6 and 7 are for debugging, I don't know if they should go upstream. Thanks, Jean
On Tue, 4 Jun 2019 11:52:18 +0100 Jean-Philippe Brucker <jean-philippe.brucker@arm.com> wrote: > On 03/06/2019 23:32, Alex Williamson wrote: > > It doesn't seem to make much sense to include this patch without > > also including "iommu: handle page response timeout". Was that one > > lost? Dropped? Lives elsewhere? > > The first 7 patches come from my sva/api branch, where I had forgotten > to add the "handle page response timeout" patch. I added it back, > probably after Eric sent this version. But I don't think the patch is > ready for upstream, as we still haven't decided how to proceed with > timeouts. Patches 6 and 7 are for debugging, I don't know if they > should go upstream. Yeah, we can wait until we all agree on timeouts. It was introduced for a basic safeguard against unresponsive guests.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 138f6664b2e2..b43f0893d252 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1813,6 +1813,14 @@ 1 - Bypass the IOMMU for DMA. unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. + iommu.prq_timeout= + Timeout in seconds to wait for page response + of a pending page request. + Format: <integer> + Default: 10 + 0 - no timeout tracking + 1 to 100 - allowed range + io7= [HW] IO7 for Marvel based alpha systems See comment before marvel_specify_io7 in arch/alpha/kernel/core_marvel.c. diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 13b301cfb10f..64e87d56f471 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -45,6 +45,19 @@ static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA; #endif static bool iommu_dma_strict __read_mostly = true; +/* + * Timeout to wait for page response of a pending page request. This is + * intended as a basic safty net in case a pending page request is not + * responded for an exceptionally long time. Device may also implement + * its own protection mechanism against this exception. + * Units are in jiffies with a range between 1 - 100 seconds equivalent. + * Default to 10 seconds. + * Setting 0 means no timeout tracking. + */ +#define IOMMU_PAGE_RESPONSE_MAX_TIMEOUT (HZ * 100) +#define IOMMU_PAGE_RESPONSE_DEF_TIMEOUT (HZ * 10) +static unsigned long prq_timeout = IOMMU_PAGE_RESPONSE_DEF_TIMEOUT; + struct iommu_group { struct kobject kobj; struct kobject *devices_kobj; @@ -157,6 +170,22 @@ static int __init iommu_dma_setup(char *str) } early_param("iommu.strict", iommu_dma_setup); +static int __init iommu_set_prq_timeout(char *str) +{ + unsigned long timeout; + + if (!str) + return -EINVAL; + timeout = simple_strtoul(str, NULL, 0); + timeout = timeout * HZ; + if (timeout > IOMMU_PAGE_RESPONSE_MAX_TIMEOUT) + return -EINVAL; + prq_timeout = timeout; + + return 0; +} +early_param("iommu.prq_timeout", iommu_set_prq_timeout); + static ssize_t iommu_group_attr_show(struct kobject *kobj, struct attribute *__attr, char *buf) {