[XEN PATCH v2 13/25] arm: new VGIC: Handle ITS related GICv3 redistributor registers

[Mykyta Poturai <Mykyta_Poturai@xxxxxxxx>]

In the GICv3 redistributor there are the PENDBASER and PROPBASER
registers which we did not emulate so far, as they only make sense
when having an ITS. In preparation for that emulate those MMIO
accesses by storing the 64-bit data written into it into a variable
which we later read in the ITS emulation.
We also sanitise the registers, making sure RES0 regions are respected
and checking for valid memory attributes.

Based on Linux commit 0aa1de57319c4 by Andre Przywara

Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>
---
 xen/arch/arm/include/asm/new_vgic.h |   3 +
 xen/arch/arm/vgic/vgic-mmio-v3.c    | 168 +++++++++++++++++++++++++++-
 2 files changed, 169 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/include/asm/new_vgic.h 
b/xen/arch/arm/include/asm/new_vgic.h
index 9eafab45ff..b037b6cf61 100644
--- a/xen/arch/arm/include/asm/new_vgic.h
+++ b/xen/arch/arm/include/asm/new_vgic.h
@@ -199,6 +199,9 @@ struct vgic_cpu {
 
     /* Cache guest interrupt ID bits */
     uint32_t num_id_bits;
+
+    /* GICR_CTLR.{ENABLE_LPIS,RWP} */
+    atomic_t ctlr;
 };
 
 static inline paddr_t vgic_cpu_base(const struct vgic_dist *vgic)
diff --git a/xen/arch/arm/vgic/vgic-mmio-v3.c b/xen/arch/arm/vgic/vgic-mmio-v3.c
index 19ebf723ee..2fb44cfe6a 100644
--- a/xen/arch/arm/vgic/vgic-mmio-v3.c
+++ b/xen/arch/arm/vgic/vgic-mmio-v3.c
@@ -42,6 +42,18 @@ unsigned long extract_bytes(uint64_t data, unsigned int 
offset,
     return (data >> (offset * 8)) & GENMASK_ULL(num * 8 - 1, 0);
 }
 
+uint64_t update_64bit_reg(u64 reg, unsigned int offset, unsigned int len,
+                          unsigned long val)
+{
+    int lower = (offset & 4) * 8;
+    int upper = lower + 8 * len - 1;
+
+    reg &= ~GENMASK_ULL(upper, lower);
+    val &= GENMASK_ULL(len * 8 - 1, 0);
+
+    return reg | ((u64)val << lower);
+}
+
 static int match_mpidr(u64 sgi_aff, u16 sgi_cpu_mask, struct vcpu *vcpu)
 {
     unsigned long affinity;
@@ -369,6 +381,158 @@ static unsigned long vgic_mmio_read_v3_idregs(struct vcpu 
*vcpu, paddr_t addr,
     return 0;
 }
 
+bool vgic_lpis_enabled(struct vcpu *vcpu)
+{
+    struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic;
+
+    return atomic_read(&vgic_cpu->ctlr) == GICR_CTLR_ENABLE_LPIS;
+}
+
+/* We want to avoid outer shareable. */
+u64 vgic_sanitise_shareability(u64 field)
+{
+    switch ( field )
+    {
+    case GIC_BASER_OuterShareable:
+        return GIC_BASER_InnerShareable;
+    default:
+        return field;
+    }
+}
+
+/* Avoid any inner non-cacheable mapping. */
+u64 vgic_sanitise_inner_cacheability(u64 field)
+{
+    switch ( field )
+    {
+    case GIC_BASER_CACHE_nCnB:
+    case GIC_BASER_CACHE_nC:
+        return GIC_BASER_CACHE_RaWb;
+    default:
+        return field;
+    }
+}
+
+/* Non-cacheable or same-as-inner are OK. */
+u64 vgic_sanitise_outer_cacheability(u64 field)
+{
+    switch ( field )
+    {
+    case GIC_BASER_CACHE_SameAsInner:
+    case GIC_BASER_CACHE_nC:
+        return field;
+    default:
+        return GIC_BASER_CACHE_SameAsInner;
+    }
+}
+
+u64 vgic_sanitise_field(u64 reg, u64 field_mask, int field_shift,
+                        u64 (*sanitise_fn)(u64))
+{
+    u64 field = (reg & field_mask) >> field_shift;
+
+    field     = sanitise_fn(field) << field_shift;
+    return (reg & ~field_mask) | field;
+}
+
+#define PROPBASER_RES0_MASK                                                    
\
+    (GENMASK_ULL(63, 59) | GENMASK_ULL(55, 52) | GENMASK_ULL(6, 5))
+#define PENDBASER_RES0_MASK                                                    
\
+    (BIT(63, ULL) | GENMASK_ULL(61, 59) | GENMASK_ULL(55, 52) |                
\
+     GENMASK_ULL(15, 12) | GENMASK_ULL(6, 0))
+
+static u64 vgic_sanitise_pendbaser(u64 reg)
+{
+    reg = vgic_sanitise_field(reg, GICR_PENDBASER_SHAREABILITY_MASK,
+                              GICR_PENDBASER_SHAREABILITY_SHIFT,
+                              vgic_sanitise_shareability);
+    reg = vgic_sanitise_field(reg, GICR_PENDBASER_INNER_CACHEABILITY_MASK,
+                              GICR_PENDBASER_INNER_CACHEABILITY_SHIFT,
+                              vgic_sanitise_inner_cacheability);
+    reg = vgic_sanitise_field(reg, GICR_PENDBASER_OUTER_CACHEABILITY_MASK,
+                              GICR_PENDBASER_OUTER_CACHEABILITY_SHIFT,
+                              vgic_sanitise_outer_cacheability);
+
+    reg &= ~PENDBASER_RES0_MASK;
+
+    return reg;
+}
+
+static u64 vgic_sanitise_propbaser(u64 reg)
+{
+    reg = vgic_sanitise_field(reg, GICR_PROPBASER_SHAREABILITY_MASK,
+                              GICR_PROPBASER_SHAREABILITY_SHIFT,
+                              vgic_sanitise_shareability);
+    reg = vgic_sanitise_field(reg, GICR_PROPBASER_INNER_CACHEABILITY_MASK,
+                              GICR_PROPBASER_INNER_CACHEABILITY_SHIFT,
+                              vgic_sanitise_inner_cacheability);
+    reg = vgic_sanitise_field(reg, GICR_PROPBASER_OUTER_CACHEABILITY_MASK,
+                              GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT,
+                              vgic_sanitise_outer_cacheability);
+
+    reg &= ~PROPBASER_RES0_MASK;
+    return reg;
+}
+
+static unsigned long vgic_mmio_read_propbase(struct vcpu *vcpu, paddr_t addr,
+                                             unsigned int len)
+{
+    struct vgic_dist *dist = &vcpu->domain->arch.vgic;
+
+    return extract_bytes(dist->propbaser, addr & 7, len);
+}
+
+static void vgic_mmio_write_propbase(struct vcpu *vcpu, paddr_t addr,
+                                     unsigned int len, unsigned long val)
+{
+    struct vgic_dist *dist = &vcpu->domain->arch.vgic;
+    u64 old_propbaser, propbaser;
+
+    /* Storing a value with LPIs already enabled is undefined */
+    if ( vgic_lpis_enabled(vcpu) )
+        return;
+
+    do
+    {
+        old_propbaser = dist->propbaser;
+        propbaser     = old_propbaser;
+        propbaser     = update_64bit_reg(propbaser, addr & 4, len, val);
+        propbaser     = vgic_sanitise_propbaser(propbaser);
+    } while ( cmpxchg64(&dist->propbaser, old_propbaser, propbaser) !=
+              old_propbaser );
+}
+
+static unsigned long vgic_mmio_read_pendbase(struct vcpu *vcpu, paddr_t addr,
+                                             unsigned int len)
+{
+    struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic;
+    u64 value                 = vgic_cpu->pendbaser;
+
+    value &= ~GICR_PENDBASER_PTZ;
+
+    return extract_bytes(value, addr & 7, len);
+}
+
+static void vgic_mmio_write_pendbase(struct vcpu *vcpu, paddr_t addr,
+                                     unsigned int len, unsigned long val)
+{
+    struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic;
+    u64 old_pendbaser, pendbaser;
+
+    /* Storing a value with LPIs already enabled is undefined */
+    if ( vgic_lpis_enabled(vcpu) )
+        return;
+
+    do
+    {
+        old_pendbaser = vgic_cpu->pendbaser;
+        pendbaser     = old_pendbaser;
+        pendbaser     = update_64bit_reg(pendbaser, addr & 4, len, val);
+        pendbaser     = vgic_sanitise_pendbaser(pendbaser);
+    } while ( cmpxchg64(&vgic_cpu->pendbaser, old_pendbaser, pendbaser) !=
+              old_pendbaser );
+}
+
 static const struct vgic_register_region vgic_v3_dist_registers[] = {
     REGISTER_DESC_WITH_LENGTH(GICD_CTLR,
         vgic_mmio_read_v3_misc, vgic_mmio_write_v3_misc,
@@ -435,10 +599,10 @@ static const struct vgic_register_region 
vgic_v3_rd_registers[] = {
         vgic_mmio_read_raz, vgic_mmio_write_wi, 4,
         VGIC_ACCESS_32bit),
     REGISTER_DESC_WITH_LENGTH(GICR_PROPBASER,
-        vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
+        vgic_mmio_read_propbase, vgic_mmio_write_propbase, 8,
         VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
     REGISTER_DESC_WITH_LENGTH(GICR_PENDBASER,
-        vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
+        vgic_mmio_read_pendbase, vgic_mmio_write_pendbase, 8,
         VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
     REGISTER_DESC_WITH_LENGTH(GICR_INVLPIR,
         vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
-- 
2.34.1