Robin Murphy
2021-Jul-09 12:56 UTC
[RFC v1 3/8] intel/vt-d: make DMAR table parsing code more flexible
On 2021-07-09 12:43, Wei Liu wrote:> Microsoft Hypervisor provides a set of hypercalls to manage device > domains. The root kernel should parse the DMAR so that it can program > the IOMMU (with hypercalls) correctly. > > The DMAR code was designed to work with Intel IOMMU only. Add two more > parameters to make it useful to Microsoft Hypervisor. Microsoft > Hypervisor does not need the DMAR parsing code to allocate an Intel > IOMMU structure; it also wishes to always reparse the DMAR table even > after it has been parsed before.We've recently defined the VIOT table for describing paravirtualised IOMMUs - would it make more sense to extend that to support the Microsoft implementation than to abuse a hardware-specific table? Am I right in assuming said hypervisor isn't intended to only ever run on Intel hardware? Robin.> Adjust Intel IOMMU code to use the new dmar_table_init. There should be > no functional change to Intel IOMMU code. > > Signed-off-by: Wei Liu <wei.liu at kernel.org> > --- > We may be able to combine alloc and force_parse? > --- > drivers/iommu/intel/dmar.c | 38 ++++++++++++++++++++--------- > drivers/iommu/intel/iommu.c | 2 +- > drivers/iommu/intel/irq_remapping.c | 2 +- > include/linux/dmar.h | 2 +- > 4 files changed, 30 insertions(+), 14 deletions(-) > > diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c > index 84057cb9596c..bd72f47c728b 100644 > --- a/drivers/iommu/intel/dmar.c > +++ b/drivers/iommu/intel/dmar.c > @@ -408,7 +408,8 @@ dmar_find_dmaru(struct acpi_dmar_hardware_unit *drhd) > * structure which uniquely represent one DMA remapping hardware unit > * present in the platform > */ > -static int dmar_parse_one_drhd(struct acpi_dmar_header *header, void *arg) > +static int dmar_parse_one_drhd_internal(struct acpi_dmar_header *header, > + void *arg, bool alloc) > { > struct acpi_dmar_hardware_unit *drhd; > struct dmar_drhd_unit *dmaru; > @@ -440,12 +441,14 @@ static int dmar_parse_one_drhd(struct acpi_dmar_header *header, void *arg) > return -ENOMEM; > } > > - ret = alloc_iommu(dmaru); > - if (ret) { > - dmar_free_dev_scope(&dmaru->devices, > - &dmaru->devices_cnt); > - kfree(dmaru); > - return ret; > + if (alloc) { > + ret = alloc_iommu(dmaru); > + if (ret) { > + dmar_free_dev_scope(&dmaru->devices, > + &dmaru->devices_cnt); > + kfree(dmaru); > + return ret; > + } > } > dmar_register_drhd_unit(dmaru); > > @@ -456,6 +459,16 @@ static int dmar_parse_one_drhd(struct acpi_dmar_header *header, void *arg) > return 0; > } > > +static int dmar_parse_one_drhd(struct acpi_dmar_header *header, void *arg) > +{ > + return dmar_parse_one_drhd_internal(header, arg, true); > +} > + > +int dmar_parse_one_drhd_noalloc(struct acpi_dmar_header *header, void *arg) > +{ > + return dmar_parse_one_drhd_internal(header, arg, false); > +} > + > static void dmar_free_drhd(struct dmar_drhd_unit *dmaru) > { > if (dmaru->devices && dmaru->devices_cnt) > @@ -633,7 +646,7 @@ static inline int dmar_walk_dmar_table(struct acpi_table_dmar *dmar, > * parse_dmar_table - parses the DMA reporting table > */ > static int __init > -parse_dmar_table(void) > +parse_dmar_table(bool alloc) > { > struct acpi_table_dmar *dmar; > int drhd_count = 0; > @@ -650,6 +663,9 @@ parse_dmar_table(void) > .cb[ACPI_DMAR_TYPE_SATC] = &dmar_parse_one_satc, > }; > > + if (!alloc) > + cb.cb[ACPI_DMAR_TYPE_HARDWARE_UNIT] = &dmar_parse_one_drhd_noalloc; > + > /* > * Do it again, earlier dmar_tbl mapping could be mapped with > * fixed map. > @@ -840,13 +856,13 @@ void __init dmar_register_bus_notifier(void) > } > > > -int __init dmar_table_init(void) > +int __init dmar_table_init(bool alloc, bool force_parse) > { > static int dmar_table_initialized; > int ret; > > - if (dmar_table_initialized == 0) { > - ret = parse_dmar_table(); > + if (dmar_table_initialized == 0 || force_parse) { > + ret = parse_dmar_table(alloc); > if (ret < 0) { > if (ret != -ENODEV) > pr_info("Parse DMAR table failure.\n"); > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > index be35284a2016..a4294d310b93 100644 > --- a/drivers/iommu/intel/iommu.c > +++ b/drivers/iommu/intel/iommu.c > @@ -4310,7 +4310,7 @@ int __init intel_iommu_init(void) > } > > down_write(&dmar_global_lock); > - if (dmar_table_init()) { > + if (dmar_table_init(true, false)) { > if (force_on) > panic("tboot: Failed to initialize DMAR table\n"); > goto out_free_dmar; > diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c > index f912fe45bea2..0e8abef862e4 100644 > --- a/drivers/iommu/intel/irq_remapping.c > +++ b/drivers/iommu/intel/irq_remapping.c > @@ -732,7 +732,7 @@ static int __init intel_prepare_irq_remapping(void) > return -ENODEV; > } > > - if (dmar_table_init() < 0) > + if (dmar_table_init(true, false) < 0) > return -ENODEV; > > if (intel_cap_audit(CAP_AUDIT_STATIC_IRQR, NULL)) > diff --git a/include/linux/dmar.h b/include/linux/dmar.h > index e04436a7ff27..f88535d41a6e 100644 > --- a/include/linux/dmar.h > +++ b/include/linux/dmar.h > @@ -106,7 +106,7 @@ static inline bool dmar_rcu_check(void) > for_each_dev_scope((devs), (cnt), (i), (tmp)) \ > if (!(tmp)) { continue; } else > > -extern int dmar_table_init(void); > +extern int dmar_table_init(bool alloc, bool force_parse); > extern int dmar_dev_scope_init(void); > extern void dmar_register_bus_notifier(void); > extern int dmar_parse_dev_scope(void *start, void *end, int *cnt, >