[Xen-devel] [PATCH v12 04/34] ARM: GICv3: setup number of LPI bits for a GICv3 guest

[Andre Przywara <andre.przywara@xxxxxxx>]

The host supports a certain number of LPI identifiers, as stored in
the GICD_TYPER register.
Store this number from the hardware register in vgic_v3_hw to allow
injecting the very same number into a guest (Dom0).
DomUs get the legacy number of 10 bits here, since for now it only sees
SPIs, so it does not need more. This should be revisited once we get
proper DomU ITS support.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/arm/gic-v3.c        |  6 +++++-
 xen/arch/arm/vgic-v3.c       | 16 +++++++++++++++-
 xen/include/asm-arm/domain.h |  1 +
 xen/include/asm-arm/vgic.h   |  3 ++-
 4 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index eda3410..fc3614e 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -1597,6 +1597,7 @@ static int __init gicv3_init(void)
 {
     int res, i;
     uint32_t reg;
+    unsigned int intid_bits;
 
     if ( !cpu_has_gicv3 )
     {
@@ -1640,8 +1641,11 @@ static int __init gicv3_init(void)
                i, r->base, r->base + r->size);
     }
 
+    reg = readl_relaxed(GICD + GICD_TYPER);
+    intid_bits = GICD_TYPE_ID_BITS(reg);
+
     vgic_v3_setup_hw(dbase, gicv3.rdist_count, gicv3.rdist_regions,
-                     gicv3.rdist_stride);
+                     gicv3.rdist_stride, intid_bits);
     gicv3_init_v2();
 
     spin_lock_init(&gicv3.lock);
diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 9018ddc..474cca7 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -57,18 +57,21 @@ static struct {
     unsigned int nr_rdist_regions;
     const struct rdist_region *regions;
     uint32_t rdist_stride; /* Re-distributor stride */
+    unsigned int intid_bits;  /* Number of interrupt ID bits */
 } vgic_v3_hw;
 
 void vgic_v3_setup_hw(paddr_t dbase,
                       unsigned int nr_rdist_regions,
                       const struct rdist_region *regions,
-                      uint32_t rdist_stride)
+                      uint32_t rdist_stride,
+                      unsigned int intid_bits)
 {
     vgic_v3_hw.enabled = 1;
     vgic_v3_hw.dbase = dbase;
     vgic_v3_hw.nr_rdist_regions = nr_rdist_regions;
     vgic_v3_hw.regions = regions;
     vgic_v3_hw.rdist_stride = rdist_stride;
+    vgic_v3_hw.intid_bits = intid_bits;
 }
 
 static struct vcpu *vgic_v3_irouter_to_vcpu(struct domain *d, uint64_t irouter)
@@ -1485,6 +1488,8 @@ static int vgic_v3_domain_init(struct domain *d)
 
             first_cpu += size / d->arch.vgic.rdist_stride;
         }
+
+        d->arch.vgic.intid_bits = vgic_v3_hw.intid_bits;
     }
     else
     {
@@ -1500,6 +1505,15 @@ static int vgic_v3_domain_init(struct domain *d)
         d->arch.vgic.rdist_regions[0].base = GUEST_GICV3_GICR0_BASE;
         d->arch.vgic.rdist_regions[0].size = GUEST_GICV3_GICR0_SIZE;
         d->arch.vgic.rdist_regions[0].first_cpu = 0;
+
+        /*
+         * TODO: only SPIs for now, adjust this when guests need LPIs.
+         * Please note that this value just describes the bits required
+         * in the stream interface, which is of no real concern for our
+         * emulation. So we just go with "10" here to cover all eventual
+         * SPIs (even if the guest implements less).
+         */
+        d->arch.vgic.intid_bits = 10;
     }
 
     ret = vgic_v3_its_init_domain(d);
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index 6de8082..7c3829d 100644
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -111,6 +111,7 @@ struct arch_domain
         uint32_t rdist_stride;              /* Re-Distributor stride */
         struct rb_root its_devices;         /* Devices mapped to an ITS */
         spinlock_t its_devices_lock;        /* Protects the its_devices tree */
+        unsigned int intid_bits;
 #endif
     } vgic;
 
diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
index 544867a..df75064 100644
--- a/xen/include/asm-arm/vgic.h
+++ b/xen/include/asm-arm/vgic.h
@@ -346,7 +346,8 @@ struct rdist_region;
 void vgic_v3_setup_hw(paddr_t dbase,
                       unsigned int nr_rdist_regions,
                       const struct rdist_region *regions,
-                      uint32_t rdist_stride);
+                      uint32_t rdist_stride,
+                      unsigned int intid_bits);
 #endif
 
 #endif /* __ASM_ARM_VGIC_H__ */
-- 
2.9.0


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