Re: [PATCH v5 09/26] KVM: arm/arm64: GICv4: Add init/teardown of the per-VM vPE irq domain

Marc Zyngier
2017-11-10T08:55:23Z

On 10/11/17 08:20, Christoffer Dall wrote:
> On Tue, Nov 07, 2017 at 02:08:23PM +0100, Auger Eric wrote:
>> Hi Marc,
>>
>> On 27/10/2017 16:28, Marc Zyngier wrote:
>>> In order to control the GICv4 view of virtual CPUs, we rely
>>> on an irqdomain allocated for that purpose. Let's add a couple
>>> of helpers to that effect.
>>>
>>> At the same time, the vgic data structures gain new fields to
>>> track all this... erm... wonderful stuff.
>>>
>>> The way we hook into the vgic init is slightly convoluted. We
>>> need the vgic to be initialized (in order to guarantee that
>>> the number of vcpus is now fixed), and we must have a vITS
>>> (otherwise this is all very pointless). So we end-up calling
>>> the init from both vgic_init and vgic_its_create.
>>>
>>> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>> ---
>>> arch/arm/kvm/Makefile | 1 +
>>> arch/arm64/kvm/Makefile | 1 +
>>> include/kvm/arm_vgic.h | 19 ++++++++++
>>> virt/kvm/arm/vgic/vgic-init.c | 9 +++++
>>> virt/kvm/arm/vgic/vgic-its.c | 8 +++++
>>> virt/kvm/arm/vgic/vgic-v4.c | 83 +++++++++++++++++++++++++++++++++++++++++++
>>> virt/kvm/arm/vgic/vgic.h | 2 ++
>>> 7 files changed, 123 insertions(+)
>>> create mode 100644 virt/kvm/arm/vgic/vgic-v4.c
>>>
>>> diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
>>> index d9beee652d36..0a1dd2cdb928 100644
>>> --- a/arch/arm/kvm/Makefile
>>> +++ b/arch/arm/kvm/Makefile
>>> @@ -31,6 +31,7 @@ obj-y += $(KVM)/arm/vgic/vgic-init.o
>>> obj-y += $(KVM)/arm/vgic/vgic-irqfd.o
>>> obj-y += $(KVM)/arm/vgic/vgic-v2.o
>>> obj-y += $(KVM)/arm/vgic/vgic-v3.o
>>> +obj-y += $(KVM)/arm/vgic/vgic-v4.o
>>> obj-y += $(KVM)/arm/vgic/vgic-mmio.o
>>> obj-y += $(KVM)/arm/vgic/vgic-mmio-v2.o
>>> obj-y += $(KVM)/arm/vgic/vgic-mmio-v3.o
>>> diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
>>> index 5d9810086c25..c30fd388ef80 100644
>>> --- a/arch/arm64/kvm/Makefile
>>> +++ b/arch/arm64/kvm/Makefile
>>> @@ -26,6 +26,7 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-init.o
>>> kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-irqfd.o
>>> kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-v2.o
>>> kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-v3.o
>>> +kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-v4.o
>>> kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-mmio.o
>>> kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-mmio-v2.o
>>> kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-mmio-v3.o
>>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>>> index ba9fb450aa1b..7eeb6c2a2f9c 100644
>>> --- a/include/kvm/arm_vgic.h
>>> +++ b/include/kvm/arm_vgic.h
>>> @@ -26,6 +26,8 @@
>>> #include <linux/list.h>
>>> #include <linux/jump_label.h>
>>>
>>> +#include <linux/irqchip/arm-gic-v4.h>
>>> +
>>> #define VGIC_V3_MAX_CPUS 255
>>> #define VGIC_V2_MAX_CPUS 8
>>> #define VGIC_NR_IRQS_LEGACY 256
>>> @@ -236,6 +238,15 @@ struct vgic_dist {
>>>
>>> /* used by vgic-debug */
>>> struct vgic_state_iter *iter;
>>> +
>>> + /*
>>> + * GICv4 ITS per-VM data, containing the IRQ domain, the VPE
>>> + * array, the property table pointer as well as allocation
>>> + * data. This essentially ties the Linux IRQ core and ITS
>>> + * together, and avoids leaking KVM's data structures anywhere
>>> + * else.
>>> + */
>>> + struct its_vm its_vm;
>>> };
>>>
>>> struct vgic_v2_cpu_if {
>>> @@ -254,6 +265,14 @@ struct vgic_v3_cpu_if {
>>> u32 vgic_ap0r[4];
>>> u32 vgic_ap1r[4];
>>> u64 vgic_lr[VGIC_V3_MAX_LRS];
>>> +
>>> + /*
>>> + * GICv4 ITS per-VPE data, containing the doorbell IRQ, the
>>> + * pending table pointer, the its_vm pointer and a few other
>>> + * HW specific things. As for the its_vm structure, this is
>>> + * linking the Linux IRQ subsystem and the ITS together.
>>> + */
>>> + struct its_vpe its_vpe;
>>> };
>>>
>>> struct vgic_cpu {
>>> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
>>> index 5801261f3add..40be908da238 100644
>>> --- a/virt/kvm/arm/vgic/vgic-init.c
>>> +++ b/virt/kvm/arm/vgic/vgic-init.c
>>> @@ -285,6 +285,12 @@ int vgic_init(struct kvm *kvm)
>>> if (ret)
>>> goto out;
>>>
>>> + if (vgic_supports_direct_msis(kvm)) {
>>> + ret = vgic_v4_init(kvm);
>>> + if (ret)
>>> + goto out;
>>> + }
>>> +
>>> kvm_for_each_vcpu(i, vcpu, kvm)
>>> kvm_vgic_vcpu_enable(vcpu);
>>>
>>> @@ -320,6 +326,9 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
>>>
>>> kfree(dist->spis);
>>> dist->nr_spis = 0;
>>> +
>>> + if (vgic_supports_direct_msis(kvm))
>>> + vgic_v4_teardown(kvm);
>>> }
>>>
>>> void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
>>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>>> index 8ee03f1e89fc..89768d2b6a91 100644
>>> --- a/virt/kvm/arm/vgic/vgic-its.c
>>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>>> @@ -1603,6 +1603,14 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
>>> if (!its)
>>> return -ENOMEM;
>>>
>>> + if (vgic_initialized(dev->kvm)) {
>> Don't we need to test vgic_supports_direct_msis() on this path too?
>>
>
> Seems to me that we should, otherwise creating an ITS after the VGIC has
> been initialized would fail on non-GICv4 compatible systems, right?
>
> How about this patch as a follow-up to the series:
>
> commit 48ec1662d0f10d6468907cdc7e12c46ca1ef497c (HEAD -> next-gicv4)
> Author: Christoffer Dall <christoffer.dall@linaro.org>
> Date: Fri Nov 10 09:16:23 2017 +0100
>
> KVM: arm/arm64: Fix GICv4 ITS initialization issues
>
> We should only try to initialize GICv4 data structures on a GICv4
> capable system. Move the vgic_supports_direct_msis() check inito
> vgic_v4_init() so that any KVM VGIC initialization path does not fail
> on non-GICv4 systems.
>
> Also be slightly more strict in the checking of the return value in
> vgic_its_create, and only error out on negative return values from the
> vgic_v4_init() function. This is important because the kvm device code
> only treats negative values as errors and only cleans up in this case.
> Errornously treating a positive return value as an error from the
> vgic_v4_init() function can lead to NULL pointer dereferences, as has
> recently been observed.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
>
> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
> index 40be908da238..62310122ee78 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -285,11 +285,9 @@ int vgic_init(struct kvm *kvm)
> if (ret)
> goto out;
>
> - if (vgic_supports_direct_msis(kvm)) {
> - ret = vgic_v4_init(kvm);
> - if (ret)
> - goto out;
> - }
> + ret = vgic_v4_init(kvm);
> + if (ret)
> + goto out;
>
> kvm_for_each_vcpu(i, vcpu, kvm)
> kvm_vgic_vcpu_enable(vcpu);
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index b8c1b724ba3e..c93ecd4a903b 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1673,7 +1673,7 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
>
> if (vgic_initialized(dev->kvm)) {
> int ret = vgic_v4_init(dev->kvm);
> - if (ret) {
> + if (ret < 0) {
> kfree(its);
> return ret;
> }
> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
> index e367d65a0ebe..bb7e31fcee35 100644
> --- a/virt/kvm/arm/vgic/vgic-v4.c
> +++ b/virt/kvm/arm/vgic/vgic-v4.c
> @@ -118,6 +118,9 @@ int vgic_v4_init(struct kvm *kvm)
> struct kvm_vcpu *vcpu;
> int i, nr_vcpus, ret;
>
> + if (!vgic_supports_direct_msis(kvm))
> + return 0; /* Nothing to see here... move along. */
> +
> if (dist->its_vm.vpes)
> return 0;
>
>

Yup, this seems like the right thing to do.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

M.
--
Jazz is not dead. It just smells funny...