> From: Tian, Kevin > Sent: Monday, September 27, 2021 9:12 AM > > > From: Lu Baolu <[email protected]> > > Sent: Sunday, September 26, 2021 7:46 PM > > > > An iommu domain could be allocated and mapped before it's attached to > > any > > device. This requires that in scalable mode, when the domain is allocated, > > the format (FL or SL) of the page table must be determined. In order to > > achieve this, the platform should support consistent SL or FL capabilities > > on all IOMMU's. This adds a check for this and aborts IOMMU probing if it > > doesn't meet this requirement. > > Is this a must? Looks the requirement comes from how the current code > is implemented. It sets DOMAIN_FLAG_USE_FIRST_LEVEL flag in > alloc_domain. But actually the pgtable is not allocated until the 1st device > is attached. If this understanding is correct, you can also postpone the flag > setting until pgtable is actually allocated.
Baolu explained to me that RMRR regions are mapped before device attach. So this check is necessary > > of course how to handle inconsistent IOMMU capabilities is another > orthogonal problem. Addressing it should not be only applied to SL/FL > difference. especially this patch doesn't check consistency. it just > checks that an IOMMU must support either SL or FL which doesn't > match the commit msg here. and the overall inconsistency check mechanism is already in place. and the logic here just extends it to cover SL/FL. Given that, Reviewed-by: Kevin Tian <[email protected]> > > > > > Signed-off-by: Lu Baolu <[email protected]> > > --- > > drivers/iommu/intel/cap_audit.h | 1 + > > drivers/iommu/intel/cap_audit.c | 13 +++++++++++++ > > 2 files changed, 14 insertions(+) > > > > diff --git a/drivers/iommu/intel/cap_audit.h > > b/drivers/iommu/intel/cap_audit.h > > index 74cfccae0e81..d07b75938961 100644 > > --- a/drivers/iommu/intel/cap_audit.h > > +++ b/drivers/iommu/intel/cap_audit.h > > @@ -111,6 +111,7 @@ bool intel_cap_smts_sanity(void); > > bool intel_cap_pasid_sanity(void); > > bool intel_cap_nest_sanity(void); > > bool intel_cap_flts_sanity(void); > > +bool intel_cap_slts_sanity(void); > > > > static inline bool scalable_mode_support(void) > > { > > diff --git a/drivers/iommu/intel/cap_audit.c > > b/drivers/iommu/intel/cap_audit.c > > index b12e421a2f1a..040e4ae0e42b 100644 > > --- a/drivers/iommu/intel/cap_audit.c > > +++ b/drivers/iommu/intel/cap_audit.c > > @@ -163,6 +163,14 @@ static int cap_audit_static(struct intel_iommu > > *iommu, enum cap_audit_type type) > > check_irq_capabilities(iommu, i); > > } > > > > + /* > > + * If the system is sane to support scalable mode, either SL or FL > > + * should be sane. > > + */ > > + if (intel_cap_smts_sanity() && > > + !intel_cap_flts_sanity() && !intel_cap_slts_sanity()) > > + return -EFAULT; > > + > > out: > > rcu_read_unlock(); > > return 0; > > @@ -203,3 +211,8 @@ bool intel_cap_flts_sanity(void) > > { > > return ecap_flts(intel_iommu_ecap_sanity); > > } > > + > > +bool intel_cap_slts_sanity(void) > > +{ > > + return ecap_slts(intel_iommu_ecap_sanity); > > +} > > -- > > 2.25.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
