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

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Commit 23bde34771 ("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: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210405163941.510258-9-eric.auger@redhat.com
This commit is contained in:
Eric Auger 2021-04-05 18:39:40 +02:00 committed by Marc Zyngier
parent e5a3563546
commit 28e9d4bce3
2 changed files with 34 additions and 25 deletions
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58
arch/arm64/kvm/vgic/vgic-mmio-v3.c
View File

@ -251,45 +251,52 @@ static void vgic_mmio_write_v3r_ctlr(struct kvm_vcpu *vcpu,
vgic_enable_lpis(vcpu);
}
static bool vgic_mmio_vcpu_rdist_is_last(struct kvm_vcpu *vcpu)
{
struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
struct vgic_redist_region *iter, *rdreg = vgic_cpu->rdreg;
if (!rdreg)
return false;
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;
/*
* 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_mmio_read_v3r_typer(struct kvm_vcpu *vcpu,
gpa_t addr, unsigned int len)
{
unsigned long mpidr = kvm_vcpu_get_mpidr_aff(vcpu);
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;
value = (u64)(mpidr & GENMASK(23, 0)) << 32;
value |= ((target_vcpu_id & 0xffff) << 8);
if (addr == last_rdist_typer)
if (vgic_has_its(vcpu->kvm))
value |= GICR_TYPER_PLPIS;
if (vgic_mmio_vcpu_rdist_is_last(vcpu))
value |= GICR_TYPER_LAST;
if (vgic_has_its(vcpu->kvm))
value |= GICR_TYPER_PLPIS;
return extract_bytes(value, addr & 7, len);
}
static unsigned long vgic_uaccess_read_v3r_typer(struct kvm_vcpu *vcpu,
gpa_t addr, unsigned int len)
{
unsigned long mpidr = kvm_vcpu_get_mpidr_aff(vcpu);
int target_vcpu_id = vcpu->vcpu_id;
u64 value;
value = (u64)(mpidr & GENMASK(23, 0)) << 32;
value |= ((target_vcpu_id & 0xffff) << 8);
if (vgic_has_its(vcpu->kvm))
value |= GICR_TYPER_PLPIS;
/* reporting of the Last bit is not supported for userspace */
return extract_bytes(value, addr & 7, len);
}
static unsigned long vgic_mmio_read_v3r_iidr(struct kvm_vcpu *vcpu,
gpa_t addr, unsigned int 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;

1
include/kvm/arm_vgic.h
View File

@ -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;