From: Auger Eric <eric.auger@redhat.com>
To: Alexandru Elisei <alexandru.elisei@arm.com>,
eric.auger.pro@gmail.com, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
maz@kernel.org, drjones@redhat.com
Cc: james.morse@arm.com, julien.thierry.kdev@gmail.com,
suzuki.poulose@arm.com, shuah@kernel.org, pbonzini@redhat.com
Subject: Re: [PATCH 8/9] KVM: arm64: vgic-v3: Expose GICR_TYPER.Last for userspace
Date: Thu, 14 Jan 2021 11:16:27 +0100 [thread overview]
Message-ID: <7078b0a5-fb18-5e65-953a-8a55009aa2be@redhat.com> (raw)
In-Reply-To: <45a364ec-eac6-a04b-9654-e97970186839@arm.com>
Hi Alexandru,
On 1/12/21 6:02 PM, Alexandru Elisei wrote:
> Hi Eric,
>
> On 12/12/20 6:50 PM, Eric Auger wrote:
>> Commit 23bde34771f1 ("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. This patch restores its
>> support (if the redistributor region was set) while keeping the
>> code safe.
>
> I suppose the reason for emulating GICR_TYPER.Last is for architecture compliance,
> right? I think that should be in the commit message.
OK added this in the commit msg.
>
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> ---
>> arch/arm64/kvm/vgic/vgic-mmio-v3.c | 7 ++++++-
>> include/kvm/arm_vgic.h | 1 +
>> 2 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
>> index 581f0f490000..2f9ef6058f6e 100644
>> --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
>> +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
>> @@ -277,6 +277,8 @@ 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);
>> + struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>> + struct vgic_redist_region *rdreg = vgic_cpu->rdreg;
>> int target_vcpu_id = vcpu->vcpu_id;
>> u64 value;
>>
>> @@ -286,7 +288,9 @@ 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 (rdreg && (vgic_cpu->rdreg_index == (rdreg->free_index - 1)))
>> + value |= GICR_TYPER_LAST;
>> +
>> return extract_bytes(value, addr & 7, len);
>> }
>>
>> @@ -714,6 +718,7 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu)
>> return -EINVAL;
>>
>> vgic_cpu->rdreg = rdreg;
>> + vgic_cpu->rdreg_index = rdreg->free_index;
>
> What happens if the next redistributor region we register has the base address
> adjacent to this one?
>
> I'm really not familiar with the code, but is it not possible to create two
> Redistributor regions (via
> KVM_DEV_ARM_VGIC_GRP_ADDR(KVM_VGIC_V3_ADDR_TYPE_REDIST)) where the second
> Redistributor region start address is immediately after the last Redistributor in
> the preceding region?
KVM_VGIC_V3_ADDR_TYPE_REDIST only allows to create a single rdist
region. Only KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION allows to register
several of them.
with KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION, it is possible to register
adjacent rdist regions. vgic_v3_rdist_free_slot() previously returned
the 1st rdist region where enough space remains for inserting the new
reg. We put the rdist at the free index there.
But maybe I misunderstood your question?
Thanks
Eric
>
> Thanks,
> Alex
>>
>> rd_base = rdreg->base + rdreg->free_index * KVM_VGIC_V3_REDIST_SIZE;
>>
>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>> index a8d8fdcd3723..596c069263a7 100644
>> --- a/include/kvm/arm_vgic.h
>> +++ b/include/kvm/arm_vgic.h
>> @@ -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;
>
next prev parent reply other threads:[~2021-01-14 10:18 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-12 18:50 [PATCH 0/9] KVM/ARM: Some vgic fixes and init sequence KVM selftests Eric Auger
2020-12-12 18:50 ` [PATCH 1/9] KVM: arm64: vgic-v3: Fix some error codes when setting RDIST base Eric Auger
2021-01-06 16:32 ` Alexandru Elisei
2021-01-14 10:02 ` Auger Eric
2020-12-12 18:50 ` [PATCH 2/9] KVM: arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION read Eric Auger
2021-01-06 17:12 ` Alexandru Elisei
2021-01-13 17:18 ` Auger Eric
2020-12-12 18:50 ` [PATCH 3/9] KVM: arm64: vgic-v3: Fix error handling in vgic_v3_set_redist_base() Eric Auger
2020-12-28 15:35 ` Marc Zyngier
2021-01-13 17:18 ` Auger Eric
2020-12-12 18:50 ` [PATCH 4/9] KVM: arm/arm64: vgic: Reset base address on kvm_vgic_dist_destroy() Eric Auger
2020-12-28 15:41 ` Marc Zyngier
2021-01-13 17:18 ` Auger Eric
2020-12-12 18:50 ` [PATCH 5/9] KVM: arm: move has_run_once after the map_resources Eric Auger
2021-01-12 14:55 ` Alexandru Elisei
2021-01-14 10:02 ` Auger Eric
2021-01-20 15:56 ` Alexandru Elisei
2021-03-12 17:27 ` Auger Eric
2020-12-12 18:50 ` [PATCH 6/9] docs: kvm: devices/arm-vgic-v3: enhance KVM_DEV_ARM_VGIC_CTRL_INIT doc Eric Auger
2021-01-12 15:39 ` Alexandru Elisei
2021-01-13 17:18 ` Auger Eric
2020-12-12 18:50 ` [PATCH 7/9] KVM: arm64: Simplify argument passing to vgic_uaccess_[read|write] Eric Auger
2021-01-12 16:04 ` Alexandru Elisei
2021-01-12 16:16 ` Alexandru Elisei
2021-01-13 17:18 ` Auger Eric
2020-12-12 18:50 ` [PATCH 8/9] KVM: arm64: vgic-v3: Expose GICR_TYPER.Last for userspace Eric Auger
2021-01-12 17:02 ` Alexandru Elisei
2021-01-14 10:16 ` Auger Eric [this message]
2021-01-20 16:13 ` Alexandru Elisei
2021-03-12 17:26 ` Auger Eric
2021-01-12 17:28 ` Alexandru Elisei
2021-01-12 17:48 ` Marc Zyngier
2020-12-12 18:50 ` [PATCH 9/9] KVM: selftests: aarch64/vgic-v3 init sequence tests Eric Auger
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