[PATCH v4 12/27] ARM: vGICv3: handle virtual LPI pending and property tables

[Andre Przywara <andre.przywara@arm.com>]

Allow a guest to provide the address and size for the memory regions
it has reserved for the GICv3 pending and property tables.
We sanitise the various fields of the respective redistributor
registers and map those pages into Xen's address space to have easy
access.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 xen/arch/arm/vgic-v3.c       | 136 +++++++++++++++++++++++++++++++++++++------
 xen/common/memory.c          |  61 +++++++++++++++++++
 xen/include/asm-arm/domain.h |   6 +-
 xen/include/asm-arm/vgic.h   |   2 +
 xen/include/xen/mm.h         |   8 +++
 5 files changed, 195 insertions(+), 18 deletions(-)

diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 797fd86..2c6b317 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -19,12 +19,14 @@
  */
 
 #include <xen/bitops.h>
+#include <xen/domain_page.h>
 #include <xen/lib.h>
 #include <xen/init.h>
 #include <xen/softirq.h>
 #include <xen/irq.h>
 #include <xen/sched.h>
 #include <xen/sizes.h>
+#include <xen/vmap.h>
 #include <asm/current.h>
 #include <asm/mmio.h>
 #include <asm/gic_v3_defs.h>
@@ -228,12 +230,15 @@ static int __vgic_v3_rdistr_rd_mmio_read(struct vcpu *v, mmio_info_t *info,
         goto read_reserved;
 
     case VREG64(GICR_PROPBASER):
-        /* LPI's not implemented */
-        goto read_as_zero_64;
+        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
+        *r = vgic_reg64_extract(v->domain->arch.vgic.rdist_propbase, info);
+        return 1;
 
     case VREG64(GICR_PENDBASER):
-        /* LPI's not implemented */
-        goto read_as_zero_64;
+        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
+        *r = vgic_reg64_extract(v->arch.vgic.rdist_pendbase, info);
+        *r &= ~GICR_PENDBASER_PTZ;       /* WO, reads as 0 */
+        return 1;
 
     case 0x0080:
         goto read_reserved;
@@ -301,11 +306,6 @@ bad_width:
     domain_crash_synchronous();
     return 0;
 
-read_as_zero_64:
-    if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
-    *r = 0;
-    return 1;
-
 read_as_zero_32:
     if ( dabt.size != DABT_WORD ) goto bad_width;
     *r = 0;
@@ -358,11 +358,95 @@ int vgic_lpi_get_priority(struct domain *d, uint32_t vlpi)
     return p->lpi_priority;
 }
 
+static uint64_t vgic_sanitise_field(uint64_t reg, uint64_t field_mask,
+                                    int field_shift,
+                                    uint64_t (*sanitise_fn)(uint64_t))
+{
+    uint64_t field = (reg & field_mask) >> field_shift;
+
+    field = sanitise_fn(field) << field_shift;
+
+    return (reg & ~field_mask) | field;
+}
+
+/* We want to avoid outer shareable. */
+static uint64_t vgic_sanitise_shareability(uint64_t field)
+{
+    switch ( field )
+    {
+    case GIC_BASER_OuterShareable:
+        return GIC_BASER_InnerShareable;
+    default:
+        return field;
+    }
+}
+
+/* Avoid any inner non-cacheable mapping. */
+static uint64_t vgic_sanitise_inner_cacheability(uint64_t 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. */
+static uint64_t vgic_sanitise_outer_cacheability(uint64_t field)
+{
+    switch ( field )
+    {
+    case GIC_BASER_CACHE_SameAsInner:
+    case GIC_BASER_CACHE_nC:
+        return field;
+    default:
+        return GIC_BASER_CACHE_nC;
+    }
+}
+
+static uint64_t sanitize_propbaser(uint64_t 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 &= ~GICR_PROPBASER_RES0_MASK;
+
+    return reg;
+}
+
+static uint64_t sanitize_pendbaser(uint64_t 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 &= ~GICR_PENDBASER_RES0_MASK;
+
+    return reg;
+}
+
 static int __vgic_v3_rdistr_rd_mmio_write(struct vcpu *v, mmio_info_t *info,
                                           uint32_t gicr_reg,
                                           register_t r)
 {
     struct hsr_dabt dabt = info->dabt;
+    uint64_t reg;
 
     switch ( gicr_reg )
     {
@@ -393,36 +477,54 @@ static int __vgic_v3_rdistr_rd_mmio_write(struct vcpu *v, mmio_info_t *info,
         goto write_impl_defined;
 
     case VREG64(GICR_SETLPIR):
-        /* LPI is not implemented */
+        /* LPIs without an ITS are not implemented */
         goto write_ignore_64;
 
     case VREG64(GICR_CLRLPIR):
-        /* LPI is not implemented */
+        /* LPIs without an ITS are not implemented */
         goto write_ignore_64;
 
     case 0x0050:
         goto write_reserved;
 
     case VREG64(GICR_PROPBASER):
-        /* LPI is not implemented */
-        goto write_ignore_64;
+        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
+
+        /* Writing PROPBASER with LPIs enabled is UNPREDICTABLE. */
+        if ( v->arch.vgic.flags & VGIC_V3_LPIS_ENABLED )
+            return 1;
+
+        reg = v->domain->arch.vgic.rdist_propbase;
+        vgic_reg64_update(&reg, r, info);
+        reg = sanitize_propbaser(reg);
+        v->domain->arch.vgic.rdist_propbase = reg;
+        return 1;
 
     case VREG64(GICR_PENDBASER):
-        /* LPI is not implemented */
-        goto write_ignore_64;
+        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
+
+        /* Writing PENDBASER with LPIs enabled is UNPREDICTABLE. */
+        if ( v->arch.vgic.flags & VGIC_V3_LPIS_ENABLED )
+            return 1;
+
+        reg = v->arch.vgic.rdist_pendbase;
+        vgic_reg64_update(&reg, r, info);
+        reg = sanitize_pendbaser(reg);
+        v->arch.vgic.rdist_pendbase = reg;
+        return 1;
 
     case 0x0080:
         goto write_reserved;
 
     case VREG64(GICR_INVLPIR):
-        /* LPI is not implemented */
+        /* LPIs without an ITS are not implemented */
         goto write_ignore_64;
 
     case 0x00A8:
         goto write_reserved;
 
     case VREG64(GICR_INVALLR):
-        /* LPI is not implemented */
+        /* LPIs without an ITS are not implemented */
         goto write_ignore_64;
 
     case 0x00B8:
diff --git a/xen/common/memory.c b/xen/common/memory.c
index ad0b33c..3ca3f60 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -1418,6 +1418,67 @@ int prepare_ring_for_helper(
 }
 
 /*
+ * Mark a given number of guest pages as used (by increasing their refcount),
+ * starting with the given guest address. This needs to be called once before
+ * calling (possibly repeatedly) map_one_guest_pages().
+ * Before the domain gets destroyed, call put_guest_pages() to drop the
+ * reference.
+ */
+int get_guest_pages(struct domain *d, paddr_t gpa, unsigned int nr_pages)
+{
+    unsigned int i;
+    struct page_info *page;
+
+    for ( i = 0; i < nr_pages; i++ )
+    {
+        page = get_page_from_gfn(d, (gpa >> PAGE_SHIFT) + i, NULL, P2M_ALLOC);
+        if ( !page )
+        {
+            /* Make sure we drop the references of pages we got so far. */
+            put_guest_pages(d, gpa, i);
+            return -EINVAL;
+        }
+    }
+
+    return 0;
+}
+
+void put_guest_pages(struct domain *d, paddr_t gpa, unsigned int nr_pages)
+{
+    mfn_t mfn;
+    int i;
+
+    p2m_read_lock(&d->arch.p2m);
+    for ( i = 0; i < nr_pages; i++ )
+    {
+        mfn = p2m_get_entry(&d->arch.p2m, _gfn((gpa >> PAGE_SHIFT) + i),
+                            NULL, NULL, NULL);
+        if ( mfn_eq(mfn, INVALID_MFN) )
+            continue;
+        put_page(mfn_to_page(mfn_x(mfn)));
+    }
+    p2m_read_unlock(&d->arch.p2m);
+}
+
+/*
+ * Provides easy access to guest memory by "mapping" one page of it into
+ * Xen's VA space. In fact it relies on the memory being already mapped
+ * and just provides a pointer to it.
+ */
+void *map_one_guest_page(struct domain *d, paddr_t guest_addr)
+{
+    void *ptr = map_domain_page(_mfn(guest_addr >> PAGE_SHIFT));
+
+    return ptr + (guest_addr & ~PAGE_MASK);
+}
+
+/* "Unmap" a previously mapped guest page. Could be optimized away. */
+void unmap_one_guest_page(void *va)
+{
+    unmap_domain_page(((uintptr_t)va & PAGE_MASK));
+}
+
+/*
  * Local variables:
  * mode: C
  * c-file-style: "BSD"
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index 6ee7538..f460457 100644
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -109,6 +109,8 @@ struct arch_domain
         } *rdist_regions;
         int nr_regions;                     /* Number of rdist regions */
         uint32_t rdist_stride;              /* Re-Distributor stride */
+        unsigned int nr_lpis;
+        uint64_t rdist_propbase;
         struct rb_root its_devices;         /* Devices mapped to an ITS */
         spinlock_t its_devices_lock;        /* Protects the its_devices tree */
         struct radix_tree_root pend_lpi_tree; /* Stores struct pending_irq's */
@@ -256,7 +258,9 @@ struct arch_vcpu
 
         /* GICv3: redistributor base and flags for this vCPU */
         paddr_t rdist_base;
-#define VGIC_V3_RDIST_LAST  (1 << 0)        /* last vCPU of the rdist */
+        uint64_t rdist_pendbase;
+#define VGIC_V3_RDIST_LAST      (1 << 0)        /* last vCPU of the rdist */
+#define VGIC_V3_LPIS_ENABLED    (1 << 1)
         uint8_t flags;
     } vgic;
 
diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
index a24a971..b5ae3e9 100644
--- a/xen/include/asm-arm/vgic.h
+++ b/xen/include/asm-arm/vgic.h
@@ -312,6 +312,8 @@ extern void register_vgic_ops(struct domain *d, const struct vgic_ops *ops);
 int vgic_v2_init(struct domain *d, int *mmio_count);
 int vgic_v3_init(struct domain *d, int *mmio_count);
 
+extern int vgic_lpi_get_priority(struct domain *d, uint32_t vlpi);
+
 extern int domain_vgic_register(struct domain *d, int *mmio_count);
 extern int vcpu_vgic_free(struct vcpu *v);
 extern bool vgic_to_sgi(struct vcpu *v, register_t sgir,
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 88de3c1..c402856 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -570,6 +570,14 @@ int prepare_ring_for_helper(struct domain *d, unsigned long gmfn,
                             struct page_info **_page, void **_va);
 void destroy_ring_for_helper(void **_va, struct page_info *page);
 
+/* Mark guest pages as used (by the hypervisor) to avoid dropping them. */
+int get_guest_pages(struct domain *d, paddr_t gpa, unsigned int nr_pages);
+void put_guest_pages(struct domain *d, paddr_t gpa, unsigned int nr_pages);
+
+/* Map guest memory into Xen's VA space. */
+void *map_one_guest_page(struct domain *d, paddr_t guest_addr);
+void unmap_one_guest_page(void *va);
+
 #include <asm/flushtlb.h>
 
 static inline void accumulate_tlbflush(bool *need_tlbflush,
-- 
2.9.0


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