KVM: arm64: vgic-its: Introduce migration ABI infrastructure

We plan to support different migration ABIs, ie. characterizing
the ITS table layout format in guest RAM. For example, a new ABI
will be needed if vLPIs get supported for nested use case.

So let's introduce an array of supported ABIs (at the moment a single
ABI is supported though). The following characteristics are foreseen
to vary with the ABI: size of table entries, save/restore operation,
the way abi settings are applied.

By default the MAX_ABI_REV is applied on its creation. In subsequent
patches we will introduce a way for the userspace to change the ABI
in use.

The entry sizes now are set according to the ABI version and not
hardcoded anymore.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 26ed4fb..fabcc64 100644 (file)
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -162,6 +162,9 @@ struct vgic_its {
        u32                     creadr;
        u32                     cwriter;
 
+       /* migration ABI revision in use */
+       u32                     abi_rev;
+
        /* Protects the device and collection lists */
        struct mutex            its_lock;
        struct list_head        device_list;

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 97cbca1..81ebe43 100644 (file)
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -132,6 +132,9 @@
 #define GIC_BASER_SHAREABILITY(reg, type)                              \
        (GIC_BASER_##type << reg##_SHAREABILITY_SHIFT)
 
+/* encode a size field of width @w containing @n - 1 units */
+#define GIC_ENCODE_SZ(n, w) (((unsigned long)(n) - 1) & GENMASK_ULL(((w) - 1), 0))
+
 #define GICR_PROPBASER_SHAREABILITY_SHIFT              (10)
 #define GICR_PROPBASER_INNER_CACHEABILITY_SHIFT                (7)
 #define GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT                (56)
@@ -232,6 +235,7 @@
 #define GITS_CTLR_QUIESCENT            (1U << 31)
 
 #define GITS_TYPER_PLPIS               (1UL << 0)
+#define GITS_TYPER_ITT_ENTRY_SIZE_SHIFT        4
 #define GITS_TYPER_IDBITS_SHIFT                8
 #define GITS_TYPER_DEVBITS_SHIFT       13
 #define GITS_TYPER_DEVBITS(r)          ((((r) >> GITS_TYPER_DEVBITS_SHIFT) & 0x1f) + 1)
@@ -290,6 +294,7 @@
 #define GITS_BASER_TYPE(r)             (((r) >> GITS_BASER_TYPE_SHIFT) & 7)
 #define GITS_BASER_ENTRY_SIZE_SHIFT            (48)
 #define GITS_BASER_ENTRY_SIZE(r)       ((((r) >> GITS_BASER_ENTRY_SIZE_SHIFT) & 0x1f) + 1)
+#define GITS_BASER_ENTRY_SIZE_MASK     GENMASK_ULL(52, 48)
 #define GITS_BASER_SHAREABILITY_SHIFT  (10)
 #define GITS_BASER_InnerShareable                                      \
        GIC_BASER_SHAREABILITY(GITS_BASER, InnerShareable)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index bf3ff09..4f6ea46 100644 (file)
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -33,6 +33,10 @@
 #include "vgic.h"
 #include "vgic-mmio.h"
 
+static int vgic_its_save_tables_v0(struct vgic_its *its);
+static int vgic_its_restore_tables_v0(struct vgic_its *its);
+static int vgic_its_commit_v0(struct vgic_its *its);
+
 /*
  * Creates a new (reference to a) struct vgic_irq for a given LPI.
  * If this LPI is already mapped on another ITS, we increase its refcount
@@ -123,6 +127,50 @@ struct its_ite {
        u32 event_id;
 };
 
+/**
+ * struct vgic_its_abi - ITS abi ops and settings
+ * @cte_esz: collection table entry size
+ * @dte_esz: device table entry size
+ * @ite_esz: interrupt translation table entry size
+ * @save tables: save the ITS tables into guest RAM
+ * @restore_tables: restore the ITS internal structs from tables
+ *  stored in guest RAM
+ * @commit: initialize the registers which expose the ABI settings,
+ *  especially the entry sizes
+ */
+struct vgic_its_abi {
+       int cte_esz;
+       int dte_esz;
+       int ite_esz;
+       int (*save_tables)(struct vgic_its *its);
+       int (*restore_tables)(struct vgic_its *its);
+       int (*commit)(struct vgic_its *its);
+};
+
+static const struct vgic_its_abi its_table_abi_versions[] = {
+       [0] = {.cte_esz = 8, .dte_esz = 8, .ite_esz = 8,
+        .save_tables = vgic_its_save_tables_v0,
+        .restore_tables = vgic_its_restore_tables_v0,
+        .commit = vgic_its_commit_v0,
+       },
+};
+
+#define NR_ITS_ABIS    ARRAY_SIZE(its_table_abi_versions)
+
+inline const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its)
+{
+       return &its_table_abi_versions[its->abi_rev];
+}
+
+int vgic_its_set_abi(struct vgic_its *its, int rev)
+{
+       const struct vgic_its_abi *abi;
+
+       its->abi_rev = rev;
+       abi = vgic_its_get_abi(its);
+       return abi->commit(its);
+}
+
 /*
  * Find and returns a device in the device table for an ITS.
  * Must be called with the its_lock mutex held.
@@ -364,6 +412,7 @@ static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm,
                                              struct vgic_its *its,
                                              gpa_t addr, unsigned int len)
 {
+       const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 reg = GITS_TYPER_PLPIS;
 
        /*
@@ -376,6 +425,7 @@ static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm,
         */
        reg |= 0x0f << GITS_TYPER_DEVBITS_SHIFT;
        reg |= 0x0f << GITS_TYPER_IDBITS_SHIFT;
+       reg |= GIC_ENCODE_SZ(abi->ite_esz, 4) << GITS_TYPER_ITT_ENTRY_SIZE_SHIFT;
 
        return extract_bytes(reg, addr & 7, len);
 }
@@ -1268,6 +1318,7 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
                                      gpa_t addr, unsigned int len,
                                      unsigned long val)
 {
+       const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 entry_size, device_type;
        u64 reg, *regptr, clearbits = 0;
 
@@ -1278,12 +1329,12 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
        switch (BASER_INDEX(addr)) {
        case 0:
                regptr = &its->baser_device_table;
-               entry_size = 8;
+               entry_size = abi->dte_esz;
                device_type = GITS_BASER_TYPE_DEVICE;
                break;
        case 1:
                regptr = &its->baser_coll_table;
-               entry_size = 8;
+               entry_size = abi->cte_esz;
                device_type = GITS_BASER_TYPE_COLLECTION;
                clearbits = GITS_BASER_INDIRECT;
                break;
@@ -1425,7 +1476,6 @@ static int vgic_register_its_iodev(struct kvm *kvm, struct vgic_its *its)
        (GIC_BASER_CACHEABILITY(GITS_BASER, INNER, RaWb)                | \
         GIC_BASER_CACHEABILITY(GITS_BASER, OUTER, SameAsInner)         | \
         GIC_BASER_SHAREABILITY(GITS_BASER, InnerShareable)             | \
-        ((8ULL - 1) << GITS_BASER_ENTRY_SIZE_SHIFT)                    | \
         GITS_BASER_PAGE_SIZE_64K)
 
 #define INITIAL_PROPBASER_VALUE                                                  \
@@ -1465,7 +1515,7 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
 
        dev->private = its;
 
-       return 0;
+       return vgic_its_set_abi(its, NR_ITS_ABIS - 1);
 }
 
 static void vgic_its_destroy(struct kvm_device *kvm_dev)
@@ -1592,6 +1642,41 @@ out:
        return ret;
 }
 
+/**
+ * vgic_its_save_tables_v0 - Save the ITS tables into guest ARM
+ * according to v0 ABI
+ */
+static int vgic_its_save_tables_v0(struct vgic_its *its)
+{
+       return -ENXIO;
+}
+
+/**
+ * vgic_its_restore_tables_v0 - Restore the ITS tables from guest RAM
+ * to internal data structs according to V0 ABI
+ *
+ */
+static int vgic_its_restore_tables_v0(struct vgic_its *its)
+{
+       return -ENXIO;
+}
+
+static int vgic_its_commit_v0(struct vgic_its *its)
+{
+       const struct vgic_its_abi *abi;
+
+       abi = vgic_its_get_abi(its);
+       its->baser_coll_table &= ~GITS_BASER_ENTRY_SIZE_MASK;
+       its->baser_device_table &= ~GITS_BASER_ENTRY_SIZE_MASK;
+
+       its->baser_coll_table |= (GIC_ENCODE_SZ(abi->cte_esz, 5)
+                                       << GITS_BASER_ENTRY_SIZE_SHIFT);
+
+       its->baser_device_table |= (GIC_ENCODE_SZ(abi->dte_esz, 5)
+                                       << GITS_BASER_ENTRY_SIZE_SHIFT);
+       return 0;
+}
+
 static int vgic_its_has_attr(struct kvm_device *dev,
                             struct kvm_device_attr *attr)
 {