When an IOMMU implements the full 16 bits worth of DID in context
entries, there's no point going through a memory base translation table.
For IOMMUs not using Caching Mode we can simply use the domain IDs
verbatim, while for Caching Mode we need to avoid DID 0.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
For the case where the memory tables are needed, xvzalloc_array() would
of course be an option to use here as well, despite this being boot time
allocations. Yet the introduction of xvmalloc() et al continues to be
stuck ...
---
v2: Use different BUILD_BUG_ON().
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -62,11 +62,32 @@ static struct tasklet vtd_fault_tasklet;
static int setup_hwdom_device(u8 devfn, struct pci_dev *);
static void setup_hwdom_rmrr(struct domain *d);
+static bool domid_mapping(const struct vtd_iommu *iommu)
+{
+ return (const void *)iommu->domid_bitmap != (const void *)iommu->domid_map;
+}
+
+static domid_t convert_domid(const struct vtd_iommu *iommu, domid_t domid)
+{
+ /*
+ * While we need to avoid DID 0 for caching-mode IOMMUs, maintain
+ * the property of the transformation being the same in either
+ * direction. By clipping to 16 bits we ensure that the resulting
+ * DID will fit in the respective context entry field.
+ */
+ BUILD_BUG_ON(DOMID_MASK >= 0xffff);
+
+ return !cap_caching_mode(iommu->cap) ? domid : ~domid;
+}
+
static int domain_iommu_domid(const struct domain *d,
const struct vtd_iommu *iommu)
{
unsigned int nr_dom, i;
+ if ( !domid_mapping(iommu) )
+ return convert_domid(iommu, d->domain_id);
+
nr_dom = cap_ndoms(iommu->cap);
i = find_first_bit(iommu->domid_bitmap, nr_dom);
while ( i < nr_dom )
@@ -91,26 +112,32 @@ static int context_set_domain_id(struct
const struct domain *d,
struct vtd_iommu *iommu)
{
- unsigned int nr_dom, i;
+ unsigned int i;
ASSERT(spin_is_locked(&iommu->lock));
- nr_dom = cap_ndoms(iommu->cap);
- i = find_first_bit(iommu->domid_bitmap, nr_dom);
- while ( i < nr_dom && iommu->domid_map[i] != d->domain_id )
- i = find_next_bit(iommu->domid_bitmap, nr_dom, i + 1);
-
- if ( i >= nr_dom )
+ if ( domid_mapping(iommu) )
{
- i = find_first_zero_bit(iommu->domid_bitmap, nr_dom);
+ unsigned int nr_dom = cap_ndoms(iommu->cap);
+
+ i = find_first_bit(iommu->domid_bitmap, nr_dom);
+ while ( i < nr_dom && iommu->domid_map[i] != d->domain_id )
+ i = find_next_bit(iommu->domid_bitmap, nr_dom, i + 1);
+
if ( i >= nr_dom )
{
- dprintk(XENLOG_ERR VTDPREFIX, "IOMMU: no free domain ids\n");
- return -EBUSY;
+ i = find_first_zero_bit(iommu->domid_bitmap, nr_dom);
+ if ( i >= nr_dom )
+ {
+ dprintk(XENLOG_ERR VTDPREFIX, "IOMMU: no free domain id\n");
+ return -EBUSY;
+ }
+ iommu->domid_map[i] = d->domain_id;
+ set_bit(i, iommu->domid_bitmap);
}
- iommu->domid_map[i] = d->domain_id;
- set_bit(i, iommu->domid_bitmap);
}
+ else
+ i = convert_domid(iommu, d->domain_id);
context->hi |= (i & ((1 << DID_FIELD_WIDTH) - 1)) << DID_HIGH_OFFSET;
return 0;
@@ -140,7 +167,12 @@ static int context_get_domain_id(const s
static void cleanup_domid_map(struct domain *domain, struct vtd_iommu *iommu)
{
- int iommu_domid = domain_iommu_domid(domain, iommu);
+ int iommu_domid;
+
+ if ( !domid_mapping(iommu) )
+ return;
+
+ iommu_domid = domain_iommu_domid(domain, iommu);
if ( iommu_domid >= 0 )
{
@@ -196,7 +228,13 @@ static void check_cleanup_domid_map(stru
domid_t did_to_domain_id(const struct vtd_iommu *iommu, unsigned int did)
{
- if ( did >= cap_ndoms(iommu->cap) || !test_bit(did, iommu->domid_bitmap) )
+ if ( did >= min(cap_ndoms(iommu->cap), DOMID_MASK + 1) )
+ return DOMID_INVALID;
+
+ if ( !domid_mapping(iommu) )
+ return convert_domid(iommu, did);
+
+ if ( !test_bit(did, iommu->domid_bitmap) )
return DOMID_INVALID;
return iommu->domid_map[did];
@@ -1297,24 +1335,32 @@ int __init iommu_alloc(struct acpi_drhd_
if ( !ecap_coherent(iommu->ecap) )
vtd_ops.sync_cache = sync_cache;
- /* allocate domain id bitmap */
nr_dom = cap_ndoms(iommu->cap);
- iommu->domid_bitmap = xzalloc_array(unsigned long, BITS_TO_LONGS(nr_dom));
- if ( !iommu->domid_bitmap )
- return -ENOMEM;
- iommu->domid_map = xzalloc_array(domid_t, nr_dom);
- if ( !iommu->domid_map )
- return -ENOMEM;
+ if ( nr_dom <= DOMID_MASK + cap_caching_mode(iommu->cap) )
+ {
+ /* Allocate domain id (bit) maps. */
+ iommu->domid_bitmap = xzalloc_array(unsigned long,
+ BITS_TO_LONGS(nr_dom));
+ iommu->domid_map = xzalloc_array(domid_t, nr_dom);
+ if ( !iommu->domid_bitmap || !iommu->domid_map )
+ return -ENOMEM;
- /*
- * If Caching mode is set, then invalid translations are tagged with
- * domain id 0. Hence reserve bit/slot 0.
- */
- if ( cap_caching_mode(iommu->cap) )
+ /*
+ * If Caching mode is set, then invalid translations are tagged
+ * with domain id 0. Hence reserve bit/slot 0.
+ */
+ if ( cap_caching_mode(iommu->cap) )
+ {
+ iommu->domid_map[0] = DOMID_INVALID;
+ __set_bit(0, iommu->domid_bitmap);
+ }
+ }
+ else
{
- iommu->domid_map[0] = DOMID_INVALID;
- __set_bit(0, iommu->domid_bitmap);
+ /* Don't leave dangling NULL pointers. */
+ iommu->domid_bitmap = ZERO_BLOCK_PTR;
+ iommu->domid_map = ZERO_BLOCK_PTR;
}
return 0;
--- a/xen/drivers/passthrough/vtd/iommu.h
+++ b/xen/drivers/passthrough/vtd/iommu.h
@@ -82,7 +82,7 @@
#define cap_plmr(c) (((c) >> 5) & 1)
#define cap_rwbf(c) (((c) >> 4) & 1)
#define cap_afl(c) (((c) >> 3) & 1)
-#define cap_ndoms(c) (1 << (4 + 2 * ((c) & 0x7)))
+#define cap_ndoms(c) (1U << (4 + 2 * ((c) & 0x7)))
/*
* Extended Capability Register
> From: Jan Beulich <jbeulich@suse.com> > Sent: Friday, December 3, 2021 6:41 PM > > When an IOMMU implements the full 16 bits worth of DID in context > entries, there's no point going through a memory base translation table. > For IOMMUs not using Caching Mode we can simply use the domain IDs > verbatim, while for Caching Mode we need to avoid DID 0. > > Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> > --- > For the case where the memory tables are needed, xvzalloc_array() would > of course be an option to use here as well, despite this being boot time > allocations. Yet the introduction of xvmalloc() et al continues to be > stuck ... > --- > v2: Use different BUILD_BUG_ON(). > > --- a/xen/drivers/passthrough/vtd/iommu.c > +++ b/xen/drivers/passthrough/vtd/iommu.c > @@ -62,11 +62,32 @@ static struct tasklet vtd_fault_tasklet; > static int setup_hwdom_device(u8 devfn, struct pci_dev *); > static void setup_hwdom_rmrr(struct domain *d); > > +static bool domid_mapping(const struct vtd_iommu *iommu) > +{ > + return (const void *)iommu->domid_bitmap != (const void *)iommu- > >domid_map; > +} > + > +static domid_t convert_domid(const struct vtd_iommu *iommu, domid_t > domid) > +{ > + /* > + * While we need to avoid DID 0 for caching-mode IOMMUs, maintain > + * the property of the transformation being the same in either > + * direction. By clipping to 16 bits we ensure that the resulting > + * DID will fit in the respective context entry field. > + */ > + BUILD_BUG_ON(DOMID_MASK >= 0xffff); > + > + return !cap_caching_mode(iommu->cap) ? domid : ~domid; > +} > + > static int domain_iommu_domid(const struct domain *d, > const struct vtd_iommu *iommu) > { > unsigned int nr_dom, i; > > + if ( !domid_mapping(iommu) ) > + return convert_domid(iommu, d->domain_id); > + > nr_dom = cap_ndoms(iommu->cap); > i = find_first_bit(iommu->domid_bitmap, nr_dom); > while ( i < nr_dom ) > @@ -91,26 +112,32 @@ static int context_set_domain_id(struct > const struct domain *d, > struct vtd_iommu *iommu) > { > - unsigned int nr_dom, i; > + unsigned int i; > > ASSERT(spin_is_locked(&iommu->lock)); > > - nr_dom = cap_ndoms(iommu->cap); > - i = find_first_bit(iommu->domid_bitmap, nr_dom); > - while ( i < nr_dom && iommu->domid_map[i] != d->domain_id ) > - i = find_next_bit(iommu->domid_bitmap, nr_dom, i + 1); > - > - if ( i >= nr_dom ) > + if ( domid_mapping(iommu) ) > { > - i = find_first_zero_bit(iommu->domid_bitmap, nr_dom); > + unsigned int nr_dom = cap_ndoms(iommu->cap); > + > + i = find_first_bit(iommu->domid_bitmap, nr_dom); > + while ( i < nr_dom && iommu->domid_map[i] != d->domain_id ) > + i = find_next_bit(iommu->domid_bitmap, nr_dom, i + 1); > + > if ( i >= nr_dom ) > { > - dprintk(XENLOG_ERR VTDPREFIX, "IOMMU: no free domain ids\n"); > - return -EBUSY; > + i = find_first_zero_bit(iommu->domid_bitmap, nr_dom); > + if ( i >= nr_dom ) > + { > + dprintk(XENLOG_ERR VTDPREFIX, "IOMMU: no free domain id\n"); > + return -EBUSY; > + } > + iommu->domid_map[i] = d->domain_id; > + set_bit(i, iommu->domid_bitmap); > } > - iommu->domid_map[i] = d->domain_id; > - set_bit(i, iommu->domid_bitmap); > } > + else > + i = convert_domid(iommu, d->domain_id); > > context->hi |= (i & ((1 << DID_FIELD_WIDTH) - 1)) << DID_HIGH_OFFSET; > return 0; > @@ -140,7 +167,12 @@ static int context_get_domain_id(const s > > static void cleanup_domid_map(struct domain *domain, struct vtd_iommu > *iommu) > { > - int iommu_domid = domain_iommu_domid(domain, iommu); > + int iommu_domid; > + > + if ( !domid_mapping(iommu) ) > + return; > + > + iommu_domid = domain_iommu_domid(domain, iommu); > > if ( iommu_domid >= 0 ) > { > @@ -196,7 +228,13 @@ static void check_cleanup_domid_map(stru > > domid_t did_to_domain_id(const struct vtd_iommu *iommu, unsigned int > did) > { > - if ( did >= cap_ndoms(iommu->cap) || !test_bit(did, iommu- > >domid_bitmap) ) > + if ( did >= min(cap_ndoms(iommu->cap), DOMID_MASK + 1) ) > + return DOMID_INVALID; > + > + if ( !domid_mapping(iommu) ) > + return convert_domid(iommu, did); > + > + if ( !test_bit(did, iommu->domid_bitmap) ) > return DOMID_INVALID; > > return iommu->domid_map[did]; > @@ -1297,24 +1335,32 @@ int __init iommu_alloc(struct acpi_drhd_ > if ( !ecap_coherent(iommu->ecap) ) > vtd_ops.sync_cache = sync_cache; > > - /* allocate domain id bitmap */ > nr_dom = cap_ndoms(iommu->cap); > - iommu->domid_bitmap = xzalloc_array(unsigned long, > BITS_TO_LONGS(nr_dom)); > - if ( !iommu->domid_bitmap ) > - return -ENOMEM; > > - iommu->domid_map = xzalloc_array(domid_t, nr_dom); > - if ( !iommu->domid_map ) > - return -ENOMEM; > + if ( nr_dom <= DOMID_MASK + cap_caching_mode(iommu->cap) ) > + { > + /* Allocate domain id (bit) maps. */ > + iommu->domid_bitmap = xzalloc_array(unsigned long, > + BITS_TO_LONGS(nr_dom)); > + iommu->domid_map = xzalloc_array(domid_t, nr_dom); > + if ( !iommu->domid_bitmap || !iommu->domid_map ) > + return -ENOMEM; > > - /* > - * If Caching mode is set, then invalid translations are tagged with > - * domain id 0. Hence reserve bit/slot 0. > - */ > - if ( cap_caching_mode(iommu->cap) ) > + /* > + * If Caching mode is set, then invalid translations are tagged > + * with domain id 0. Hence reserve bit/slot 0. > + */ > + if ( cap_caching_mode(iommu->cap) ) > + { > + iommu->domid_map[0] = DOMID_INVALID; > + __set_bit(0, iommu->domid_bitmap); > + } > + } > + else > { > - iommu->domid_map[0] = DOMID_INVALID; > - __set_bit(0, iommu->domid_bitmap); > + /* Don't leave dangling NULL pointers. */ > + iommu->domid_bitmap = ZERO_BLOCK_PTR; > + iommu->domid_map = ZERO_BLOCK_PTR; > } > > return 0; > --- a/xen/drivers/passthrough/vtd/iommu.h > +++ b/xen/drivers/passthrough/vtd/iommu.h > @@ -82,7 +82,7 @@ > #define cap_plmr(c) (((c) >> 5) & 1) > #define cap_rwbf(c) (((c) >> 4) & 1) > #define cap_afl(c) (((c) >> 3) & 1) > -#define cap_ndoms(c) (1 << (4 + 2 * ((c) & 0x7))) > +#define cap_ndoms(c) (1U << (4 + 2 * ((c) & 0x7))) > > /* > * Extended Capability Register
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