Commit 28e9d4bc authored by Eric Auger's avatar Eric Auger Committed by Marc Zyngier
Browse files

KVM: arm64: vgic-v3: Expose GICR_TYPER.Last for userspace 



Commit 23bde347 ("KVM: arm64: vgic-v3: Drop the
reporting of GICR_TYPER.Last for userspace") temporarily fixed
a bug identified when attempting to access the GICR_TYPER
register before the redistributor region setting, but dropped
the support of the LAST bit.

Emulating the GICR_TYPER.Last bit still makes sense for
architecture compliance though. This patch restores its support
(if the redistributor region was set) while keeping the code safe.

We introduce a new helper, vgic_mmio_vcpu_rdist_is_last() which
computes whether a redistributor is the highest one of a series
of redistributor contributor pages.

With this new implementation we do not need to have a uaccess
read accessor anymore.

Signed-off-by: default avatarEric Auger <eric.auger@redhat.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210405163941.510258-9-eric.auger@redhat.com
parent e5a35635

arch/arm64/kvm/vgic/vgic-mmio-v3.c

+27 −19
Original line number Diff line number Diff line
@@ -251,29 +251,34 @@ static void vgic_mmio_write_v3r_ctlr(struct kvm_vcpu *vcpu, 
		vgic_enable_lpis(vcpu);

}



static unsigned long vgic_mmio_read_v3r_typer(struct kvm_vcpu *vcpu,

					      gpa_t addr, unsigned int len)

static bool vgic_mmio_vcpu_rdist_is_last(struct kvm_vcpu *vcpu)

{

	unsigned long mpidr = kvm_vcpu_get_mpidr_aff(vcpu);

	struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;

	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;

	struct vgic_redist_region *rdreg = vgic_cpu->rdreg;

	int target_vcpu_id = vcpu->vcpu_id;

	gpa_t last_rdist_typer = rdreg->base + GICR_TYPER +

			(rdreg->free_index - 1) * KVM_VGIC_V3_REDIST_SIZE;

	u64 value;

	struct vgic_redist_region *iter, *rdreg = vgic_cpu->rdreg;



	value = (u64)(mpidr & GENMASK(23, 0)) << 32;

	value |= ((target_vcpu_id & 0xffff) << 8);

	if (!rdreg)

		return false;



	if (addr == last_rdist_typer)

		value |= GICR_TYPER_LAST;

	if (vgic_has_its(vcpu->kvm))

		value |= GICR_TYPER_PLPIS;

	if (vgic_cpu->rdreg_index < rdreg->free_index - 1) {

		return false;

	} else if (rdreg->count && vgic_cpu->rdreg_index == (rdreg->count - 1)) {

		struct list_head *rd_regions = &vgic->rd_regions;

		gpa_t end = rdreg->base + rdreg->count * KVM_VGIC_V3_REDIST_SIZE;



	return extract_bytes(value, addr & 7, len);

		/*

		 * the rdist is the last one of the redist region,

		 * check whether there is no other contiguous rdist region

		 */

		list_for_each_entry(iter, rd_regions, list) {

			if (iter->base == end && iter->free_index > 0)

				return false;

		}

	}

	return true;

}



static unsigned long vgic_uaccess_read_v3r_typer(struct kvm_vcpu *vcpu,

static unsigned long vgic_mmio_read_v3r_typer(struct kvm_vcpu *vcpu,

					      gpa_t addr, unsigned int len)

{

	unsigned long mpidr = kvm_vcpu_get_mpidr_aff(vcpu);
@@ -286,7 +291,9 @@ static unsigned long vgic_uaccess_read_v3r_typer(struct kvm_vcpu *vcpu, 
	if (vgic_has_its(vcpu->kvm))

		value |= GICR_TYPER_PLPIS;



	/* reporting of the Last bit is not supported for userspace */

	if (vgic_mmio_vcpu_rdist_is_last(vcpu))

		value |= GICR_TYPER_LAST;



	return extract_bytes(value, addr & 7, len);

}
@@ -612,7 +619,7 @@ static const struct vgic_register_region vgic_v3_rd_registers[] = { 
		VGIC_ACCESS_32bit),

	REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_TYPER,

		vgic_mmio_read_v3r_typer, vgic_mmio_write_wi,

		vgic_uaccess_read_v3r_typer, vgic_mmio_uaccess_write_wi, 8,

		NULL, vgic_mmio_uaccess_write_wi, 8,

		VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),

	REGISTER_DESC_WITH_LENGTH(GICR_WAKER,

		vgic_mmio_read_raz, vgic_mmio_write_wi, 4,
@@ -714,6 +721,7 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu) 
		return -EINVAL;



	vgic_cpu->rdreg = rdreg;

	vgic_cpu->rdreg_index = rdreg->free_index;



	rd_base = rdreg->base + rdreg->free_index * KVM_VGIC_V3_REDIST_SIZE;

include/kvm/arm_vgic.h

+1 −0
Original line number Diff line number Diff line
@@ -322,6 +322,7 @@ struct vgic_cpu { 
	 */

	struct vgic_io_device	rd_iodev;

	struct vgic_redist_region *rdreg;

	u32 rdreg_index;



	/* Contains the attributes and gpa of the LPI pending tables. */

	u64 pendbaser;