Messages in this thread | | | Subject | Re: [RFC PATCH v3 1/2] iommu: Add capability IOMMU_CAP_VIOMMU | From | Lu Baolu <> | Date | Fri, 15 Jan 2021 07:49:47 +0800 |
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Hi Leon,
On 1/14/21 9:26 PM, Leon Romanovsky wrote: > On Thu, Jan 14, 2021 at 09:30:02AM +0800, Lu Baolu wrote: >> Some vendor IOMMU drivers are able to declare that it is running in a VM >> context. This is very valuable for the features that only want to be >> supported on bare metal. Add a capability bit so that it could be used. > > And how is it used? Who and how will set it?
Use the existing iommu_capable(). I should add more descriptions about who and how to use it.
> >> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> --- >> drivers/iommu/intel/iommu.c | 20 ++++++++++++++++++++ >> drivers/iommu/virtio-iommu.c | 9 +++++++++ >> include/linux/iommu.h | 1 + >> 3 files changed, 30 insertions(+) >> >> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >> index cb205a04fe4c..8eb022d0e8aa 100644 >> --- a/drivers/iommu/intel/iommu.c >> +++ b/drivers/iommu/intel/iommu.c >> @@ -5738,12 +5738,32 @@ static inline bool nested_mode_support(void) >> return ret; >> } >> >> +static inline bool caching_mode_enabled(void) >> +{ > > Kernel coding style is not in favour of inline functions in *.c files.
Yes, agreed.
Best regards, baolu
> >> + struct dmar_drhd_unit *drhd; >> + struct intel_iommu *iommu; >> + bool ret = false; >> + >> + rcu_read_lock(); >> + for_each_active_iommu(iommu, drhd) { >> + if (cap_caching_mode(iommu->cap)) { >> + ret = true; >> + break; >> + } >> + } >> + rcu_read_unlock(); >> + >> + return ret; >> +} >> + >> static bool intel_iommu_capable(enum iommu_cap cap) >> { >> if (cap == IOMMU_CAP_CACHE_COHERENCY) >> return domain_update_iommu_snooping(NULL) == 1; >> if (cap == IOMMU_CAP_INTR_REMAP) >> return irq_remapping_enabled == 1; >> + if (cap == IOMMU_CAP_VIOMMU) >> + return caching_mode_enabled(); >> >> return false; >> } >> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c >> index 2bfdd5734844..719793e103db 100644 >> --- a/drivers/iommu/virtio-iommu.c >> +++ b/drivers/iommu/virtio-iommu.c >> @@ -931,7 +931,16 @@ static int viommu_of_xlate(struct device *dev, struct of_phandle_args *args) >> return iommu_fwspec_add_ids(dev, args->args, 1); >> } >> >> +static bool viommu_capable(enum iommu_cap cap) >> +{ >> + if (cap == IOMMU_CAP_VIOMMU) >> + return true; >> + >> + return false; >> +} >> + >> static struct iommu_ops viommu_ops = { >> + .capable = viommu_capable, >> .domain_alloc = viommu_domain_alloc, >> .domain_free = viommu_domain_free, >> .attach_dev = viommu_attach_dev, >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h >> index b95a6f8db6ff..1d24be667a03 100644 >> --- a/include/linux/iommu.h >> +++ b/include/linux/iommu.h >> @@ -94,6 +94,7 @@ enum iommu_cap { >> transactions */ >> IOMMU_CAP_INTR_REMAP, /* IOMMU supports interrupt isolation */ >> IOMMU_CAP_NOEXEC, /* IOMMU_NOEXEC flag */ >> + IOMMU_CAP_VIOMMU, /* IOMMU can declar running in a VM */ >> }; >> >> /* >> -- >> 2.25.1 >>
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