KVM: arm64: vgic-its: Implement vgic_mmio_uaccess_write_its_iidr

The GITS_IIDR revision field is used to encode the migration ABI
revision. So we need to restore it to check the table layout is
readable by the destination.

By writing the IIDR, userspace thus forces the ABI revision to be
used and this must be less than or equal to the max revision KVM
supports.

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

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 81ebe437ccc3cb59d2723c5bb544d6e9f64c2c04..2eaea308f00397f6033d7ea0394271415606ee21 100644 (file)
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -242,6 +242,11 @@
 #define GITS_TYPER_PTA                 (1UL << 19)
 #define GITS_TYPER_HWCOLLCNT_SHIFT     24
 
+#define GITS_IIDR_REV_SHIFT            12
+#define GITS_IIDR_REV_MASK             (0xf << GITS_IIDR_REV_SHIFT)
+#define GITS_IIDR_REV(r)               (((r) >> GITS_IIDR_REV_SHIFT) & 0xf)
+#define GITS_IIDR_PRODUCTID_SHIFT      24
+
 #define GITS_CBASER_VALID                      (1ULL << 63)
 #define GITS_CBASER_SHAREABILITY_SHIFT         (10)
 #define GITS_CBASER_INNER_CACHEABILITY_SHIFT   (59)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 4f6ea46c496c83577dd4a4faaa885a0f81f28337..9338efb79a547a8dbb1d582a2654ebf1967c5197 100644 (file)
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -434,7 +434,23 @@ static unsigned long vgic_mmio_read_its_iidr(struct kvm *kvm,
                                             struct vgic_its *its,
                                             gpa_t addr, unsigned int len)
 {
-       return (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
+       u32 val;
+
+       val = (its->abi_rev << GITS_IIDR_REV_SHIFT) & GITS_IIDR_REV_MASK;
+       val |= (PRODUCT_ID_KVM << GITS_IIDR_PRODUCTID_SHIFT) | IMPLEMENTER_ARM;
+       return val;
+}
+
+static int vgic_mmio_uaccess_write_its_iidr(struct kvm *kvm,
+                                           struct vgic_its *its,
+                                           gpa_t addr, unsigned int len,
+                                           unsigned long val)
+{
+       u32 rev = GITS_IIDR_REV(val);
+
+       if (rev >= NR_ITS_ABIS)
+               return -EINVAL;
+       return vgic_its_set_abi(its, rev);
 }
 
 static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
@@ -1415,8 +1431,9 @@ static struct vgic_register_region its_registers[] = {
        REGISTER_ITS_DESC(GITS_CTLR,
                vgic_mmio_read_its_ctlr, vgic_mmio_write_its_ctlr, 4,
                VGIC_ACCESS_32bit),
-       REGISTER_ITS_DESC(GITS_IIDR,
-               vgic_mmio_read_its_iidr, its_mmio_write_wi, 4,
+       REGISTER_ITS_DESC_UACCESS(GITS_IIDR,
+               vgic_mmio_read_its_iidr, its_mmio_write_wi,
+               vgic_mmio_uaccess_write_its_iidr, 4,
                VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC(GITS_TYPER,
                vgic_mmio_read_its_typer, its_mmio_write_wi, 8,