[Xen-devel] [PATCH v4 19/27] ARM: vITS: handle MAPD command

[Andre Przywara <andre.przywara@xxxxxxx>]

The MAPD command maps a device by associating a memory region for
storing ITEs with a certain device ID.
We store the given guest physical address in the device table, and, if
this command comes from Dom0, tell the host ITS driver about this new
mapping, so it can issue the corresponing host MAPD command and create
the required tables.
We don't map the device tables permanently, as their alignment
requirement is only 256 Bytes, thus making mapping of several tables
complicated. Instead we map the device tables on demand when we need
them later.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/arch/arm/vgic-v3-its.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
index 639fbbf..0e636de 100644
--- a/xen/arch/arm/vgic-v3-its.c
+++ b/xen/arch/arm/vgic-v3-its.c
@@ -42,6 +42,7 @@
 #define VIRT_ITS_CMDBUF_VALID   3
 struct virt_its {
     struct domain *d;
+    paddr_t doorbell_address;
     spinlock_t vcmd_lock;       /* Protects the virtual command buffer. */
     uint64_t cbaser;
     uint64_t cwriter;
@@ -142,6 +143,27 @@ static struct vcpu *get_vcpu_from_collection(struct 
virt_its *its,
 #define DEV_TABLE_ENTRY(addr, bits)                     \
         (((addr) & GENMASK_ULL(51, 8)) | (((bits) - 1) & GENMASK_ULL(7, 0)))
 
+/* Set the address of an ITT for a given device ID. */
+static int its_set_itt_address(struct virt_its *its, uint32_t devid,
+                               paddr_t itt_address, uint32_t nr_bits)
+{
+    paddr_t addr = get_baser_phys_addr(its->baser_dev);
+    uint64_t *itt;
+
+    if ( devid >= its->max_devices )
+        return -ENOENT;
+
+    itt = map_one_guest_page(its->d, addr + devid * sizeof(uint64_t));
+    if ( !itt )
+        return -EFAULT;
+
+    *itt = DEV_TABLE_ENTRY(itt_address, nr_bits);
+
+    unmap_one_guest_page(itt);
+
+    return 0;
+}
+
 /*
  * Lookup the address of the Interrupt Translation Table associated with
  * a device ID and return the address of the ITTE belonging to the event ID
@@ -367,6 +389,44 @@ static int its_handle_mapc(struct virt_its *its, uint64_t 
*cmdptr)
     return 0;
 }
 
+static int its_handle_mapd(struct virt_its *its, uint64_t *cmdptr)
+{
+    uint32_t devid = its_cmd_get_deviceid(cmdptr);
+    unsigned int size = its_cmd_get_size(cmdptr) + 1;
+    bool valid = its_cmd_get_validbit(cmdptr);
+    paddr_t itt_addr = its_cmd_mask_field(cmdptr, 2, 0, 52) &
+                           GENMASK_ULL(51, 8);
+    int ret;
+
+    /*
+     * There is no easy and clean way for Xen to know the ITS device ID of a
+     * particular (PCI) device, so we have to rely on the guest telling
+     * us about it. For *now* we are just using the device ID *Dom0* uses,
+     * because the driver there has the actual knowledge.
+     * Eventually this will be replaced with a dedicated hypercall to
+     * announce pass-through of devices.
+     */
+    if ( is_hardware_domain(its->d) )
+    {
+        /* Dom0's ITSes are mapped 1:1, so both address are the same. */
+        ret = gicv3_its_map_guest_device(its->d, its->doorbell_address, devid,
+                                         its->doorbell_address, devid,
+                                         BIT(size), valid);
+        if ( ret )
+            return ret;
+    }
+
+    spin_lock(&its->its_lock);
+    if ( valid )
+        ret = its_set_itt_address(its, devid, itt_addr, size);
+    else
+        ret = its_set_itt_address(its, devid, INVALID_PADDR, 1);
+
+    spin_unlock(&its->its_lock);
+
+    return ret;
+}
+
 #define ITS_CMD_BUFFER_SIZE(baser)      ((((baser) & 0xff) + 1) << 12)
 
 static int vgic_its_handle_cmds(struct domain *d, struct virt_its *its,
@@ -413,6 +473,9 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
virt_its *its,
         case GITS_CMD_MAPC:
             ret = its_handle_mapc(its, cmdptr);
             break;
+        case GITS_CMD_MAPD:
+            ret = its_handle_mapd(its, cmdptr);
+           break;
         case GITS_CMD_SYNC:
             /* We handle ITS commands synchronously, so we ignore SYNC. */
            break;
-- 
2.9.0


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