* [PATCH] KVM: arm64: Set/unset vGIC v4 forwarding if direct IRQs are supported
@ 2025-07-28 22:37 Raghavendra Rao Ananta
2025-07-29 14:37 ` Oliver Upton
0 siblings, 1 reply; 4+ messages in thread
From: Raghavendra Rao Ananta @ 2025-07-28 22:37 UTC (permalink / raw)
To: Oliver Upton, Marc Zyngier
Cc: Raghavendra Rao Anata, linux-arm-kernel, kvmarm, linux-kernel,
kvm
Commit <c652887a9288> ("KVM: arm64: vgic-v3: Allow userspace to write
GICD_TYPER2.nASSGIcap") bundles the vLPIs and vSGIs behind the
GICD_TYPER2.nASSGIcap field. While the vGIC v4 initialization and
teardown is handled correctly, it erroneously left out the cases when
KVM sets/unset vGIC v4 forwarding, which leads to a kernel panic of the
following nature:
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a8
Mem abort info:
ESR = 0x0000000096000044
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000
CM = 0, WnR = 1, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=00000073a453b000
[00000000000000a8] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000044 [#1] SMP
pstate: 23400009 (nzCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : its_irq_set_vcpu_affinity+0x58c/0x95c
lr : its_irq_set_vcpu_affinity+0x1e0/0x95c
sp : ffff8001029bb9e0
pmr_save: 00000060
x29: ffff8001029bba20 x28: ffff0001ca5e28c0 x27: 0000000000000000
x26: 0000000000000000 x25: ffff00019eee9f80 x24: ffff0001992b3f00
x23: ffff8001029bbab8 x22: ffff00001159fb80 x21: 00000000000024a7
x20: 00000000000024a7 x19: ffff00019eee9fb4 x18: 0000000000000494
x17: 000000000000000e x16: 0000000000000494 x15: 0000000000000002
x14: ffff0001a7f34600 x13: ffffccaad1203000 x12: 0000000000000018
x11: ffff000011991000 x10: 0000000000000000 x9 : 00000000000000a2
x8 : 00000000000020a8 x7 : 0000000000000000 x6 : 000000000000003f
x5 : 0000000000000040 x4 : 0000000000000000 x3 : 0000000000000004
x2 : 0000000000000000 x1 : ffff8001029bbab8 x0 : 00000000000000a8
Call trace:
its_irq_set_vcpu_affinity+0x58c/0x95c
irq_set_vcpu_affinity+0x74/0xc8
its_map_vlpi+0x4c/0x94
kvm_vgic_v4_set_forwarding+0x134/0x298
kvm_arch_irq_bypass_add_producer+0x28/0x34
irq_bypass_register_producer+0xf8/0x1d8
vfio_msi_set_vector_signal+0x2c8/0x308
vfio_pci_set_msi_trigger+0x198/0x2d4
vfio_pci_set_irqs_ioctl+0xf0/0x104
vfio_pci_core_ioctl+0x6ac/0xc5c
vfio_device_fops_unl_ioctl+0x128/0x370
__arm64_sys_ioctl+0x98/0xd0
el0_svc_common+0xd8/0x1d8
do_el0_svc+0x28/0x34
el0_svc+0x40/0xb8
el0t_64_sync_handler+0x70/0xbc
el0t_64_sync+0x1a8/0x1ac
Code: 321f0129 f940094a 8b080148 d1400900 (39000009)
---[ end trace 0000000000000000 ]---
Fix this by checking if vgic_supports_direct_irqs() while
setting/unsetting vGIC v4 forwarding as well.
Fixes: c652887a9288 ("KVM: arm64: vgic-v3: Allow userspace to write GICD_TYPER2.nASSGIcap")
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
arch/arm64/kvm/vgic/vgic-v4.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
index e7e284d47a77..873a190bcff7 100644
--- a/arch/arm64/kvm/vgic/vgic-v4.c
+++ b/arch/arm64/kvm/vgic/vgic-v4.c
@@ -433,7 +433,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq,
unsigned long flags;
int ret = 0;
- if (!vgic_supports_direct_msis(kvm))
+ if (!vgic_supports_direct_irqs(kvm))
return 0;
/*
@@ -533,7 +533,7 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int host_irq)
unsigned long flags;
int ret = 0;
- if (!vgic_supports_direct_msis(kvm))
+ if (!vgic_supports_direct_irqs(kvm))
return 0;
irq = __vgic_host_irq_get_vlpi(kvm, host_irq);
base-commit: 18ec25dd0e97653cdb576bb1750c31acf2513ea7
--
2.50.1.487.gc89ff58d15-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: arm64: Set/unset vGIC v4 forwarding if direct IRQs are supported
2025-07-28 22:37 [PATCH] KVM: arm64: Set/unset vGIC v4 forwarding if direct IRQs are supported Raghavendra Rao Ananta
@ 2025-07-29 14:37 ` Oliver Upton
2025-07-29 16:56 ` Raghavendra Rao Ananta
0 siblings, 1 reply; 4+ messages in thread
From: Oliver Upton @ 2025-07-29 14:37 UTC (permalink / raw)
To: Raghavendra Rao Ananta
Cc: Marc Zyngier, linux-arm-kernel, kvmarm, linux-kernel, kvm
Hi Raghu,
Thanks for reporting this so quickly :)
On Mon, Jul 28, 2025 at 10:37:10PM +0000, Raghavendra Rao Ananta wrote:
> diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
> index e7e284d47a77..873a190bcff7 100644
> --- a/arch/arm64/kvm/vgic/vgic-v4.c
> +++ b/arch/arm64/kvm/vgic/vgic-v4.c
> @@ -433,7 +433,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq,
> unsigned long flags;
> int ret = 0;
>
> - if (!vgic_supports_direct_msis(kvm))
> + if (!vgic_supports_direct_irqs(kvm))
> return 0;
>
> /*
> @@ -533,7 +533,7 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int host_irq)
> unsigned long flags;
> int ret = 0;
>
> - if (!vgic_supports_direct_msis(kvm))
> + if (!vgic_supports_direct_irqs(kvm))
> return 0;
I'm not sure this is what we want, since a precondition of actually
doing vLPI injection is the guest having an ITS. Could you try the
following?
Thanks,
Oliver
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index a3ef185209e9..70d50c77e5dc 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -50,6 +50,14 @@ bool vgic_has_its(struct kvm *kvm)
bool vgic_supports_direct_msis(struct kvm *kvm)
{
+ /*
+ * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware,
+ * indirectly allowing userspace to control whether or not vPEs are
+ * allocated for the VM.
+ */
+ if (system_supports_direct_sgis() && !vgic_supports_direct_sgis(kvm))
+ return false;
+
return kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm);
}
diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
index 1384a04c0784..de1c1d3261c3 100644
--- a/arch/arm64/kvm/vgic/vgic.h
+++ b/arch/arm64/kvm/vgic/vgic.h
@@ -396,15 +396,7 @@ bool vgic_supports_direct_sgis(struct kvm *kvm);
static inline bool vgic_supports_direct_irqs(struct kvm *kvm)
{
- /*
- * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware,
- * indirectly allowing userspace to control whether or not vPEs are
- * allocated for the VM.
- */
- if (system_supports_direct_sgis())
- return vgic_supports_direct_sgis(kvm);
-
- return vgic_supports_direct_msis(kvm);
+ return vgic_supports_direct_msis(kvm) || vgic_supports_direct_sgis(kvm);
}
int vgic_v4_init(struct kvm *kvm);
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: arm64: Set/unset vGIC v4 forwarding if direct IRQs are supported
2025-07-29 14:37 ` Oliver Upton
@ 2025-07-29 16:56 ` Raghavendra Rao Ananta
2025-07-29 18:02 ` Oliver Upton
0 siblings, 1 reply; 4+ messages in thread
From: Raghavendra Rao Ananta @ 2025-07-29 16:56 UTC (permalink / raw)
To: Oliver Upton; +Cc: Marc Zyngier, linux-arm-kernel, kvmarm, linux-kernel, kvm
On Tue, Jul 29, 2025 at 7:37 AM Oliver Upton <oliver.upton@linux.dev> wrote:
>
> Hi Raghu,
>
> Thanks for reporting this so quickly :)
>
> On Mon, Jul 28, 2025 at 10:37:10PM +0000, Raghavendra Rao Ananta wrote:
> > diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
> > index e7e284d47a77..873a190bcff7 100644
> > --- a/arch/arm64/kvm/vgic/vgic-v4.c
> > +++ b/arch/arm64/kvm/vgic/vgic-v4.c
> > @@ -433,7 +433,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq,
> > unsigned long flags;
> > int ret = 0;
> >
> > - if (!vgic_supports_direct_msis(kvm))
> > + if (!vgic_supports_direct_irqs(kvm))
> > return 0;
> >
> > /*
> > @@ -533,7 +533,7 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int host_irq)
> > unsigned long flags;
> > int ret = 0;
> >
> > - if (!vgic_supports_direct_msis(kvm))
> > + if (!vgic_supports_direct_irqs(kvm))
> > return 0;
>
> I'm not sure this is what we want, since a precondition of actually
> doing vLPI injection is the guest having an ITS. Could you try the
> following?
>
> Thanks,
> Oliver
>
> diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> index a3ef185209e9..70d50c77e5dc 100644
> --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> @@ -50,6 +50,14 @@ bool vgic_has_its(struct kvm *kvm)
>
> bool vgic_supports_direct_msis(struct kvm *kvm)
> {
> + /*
> + * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware,
> + * indirectly allowing userspace to control whether or not vPEs are
> + * allocated for the VM.
> + */
> + if (system_supports_direct_sgis() && !vgic_supports_direct_sgis(kvm))
> + return false;
> +
> return kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm);
> }
>
> diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
> index 1384a04c0784..de1c1d3261c3 100644
> --- a/arch/arm64/kvm/vgic/vgic.h
> +++ b/arch/arm64/kvm/vgic/vgic.h
> @@ -396,15 +396,7 @@ bool vgic_supports_direct_sgis(struct kvm *kvm);
>
> static inline bool vgic_supports_direct_irqs(struct kvm *kvm)
> {
> - /*
> - * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware,
> - * indirectly allowing userspace to control whether or not vPEs are
> - * allocated for the VM.
> - */
> - if (system_supports_direct_sgis())
> - return vgic_supports_direct_sgis(kvm);
> -
> - return vgic_supports_direct_msis(kvm);
> + return vgic_supports_direct_msis(kvm) || vgic_supports_direct_sgis(kvm);
> }
>
> int vgic_v4_init(struct kvm *kvm);
Yes, the diff seems fine (tested as well). Would you be pushing a v2
or do you want me to (on your behalf)?
Thank you.
Raghavendra
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: arm64: Set/unset vGIC v4 forwarding if direct IRQs are supported
2025-07-29 16:56 ` Raghavendra Rao Ananta
@ 2025-07-29 18:02 ` Oliver Upton
0 siblings, 0 replies; 4+ messages in thread
From: Oliver Upton @ 2025-07-29 18:02 UTC (permalink / raw)
To: Raghavendra Rao Ananta
Cc: Marc Zyngier, linux-arm-kernel, kvmarm, linux-kernel, kvm
On Tue, Jul 29, 2025 at 09:56:12AM -0700, Raghavendra Rao Ananta wrote:
> On Tue, Jul 29, 2025 at 7:37 AM Oliver Upton <oliver.upton@linux.dev> wrote:
> >
> > Hi Raghu,
> >
> > Thanks for reporting this so quickly :)
> >
> > On Mon, Jul 28, 2025 at 10:37:10PM +0000, Raghavendra Rao Ananta wrote:
> > > diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
> > > index e7e284d47a77..873a190bcff7 100644
> > > --- a/arch/arm64/kvm/vgic/vgic-v4.c
> > > +++ b/arch/arm64/kvm/vgic/vgic-v4.c
> > > @@ -433,7 +433,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq,
> > > unsigned long flags;
> > > int ret = 0;
> > >
> > > - if (!vgic_supports_direct_msis(kvm))
> > > + if (!vgic_supports_direct_irqs(kvm))
> > > return 0;
> > >
> > > /*
> > > @@ -533,7 +533,7 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int host_irq)
> > > unsigned long flags;
> > > int ret = 0;
> > >
> > > - if (!vgic_supports_direct_msis(kvm))
> > > + if (!vgic_supports_direct_irqs(kvm))
> > > return 0;
> >
> > I'm not sure this is what we want, since a precondition of actually
> > doing vLPI injection is the guest having an ITS. Could you try the
> > following?
> >
> > Thanks,
> > Oliver
> >
> > diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> > index a3ef185209e9..70d50c77e5dc 100644
> > --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> > +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> > @@ -50,6 +50,14 @@ bool vgic_has_its(struct kvm *kvm)
> >
> > bool vgic_supports_direct_msis(struct kvm *kvm)
> > {
> > + /*
> > + * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware,
> > + * indirectly allowing userspace to control whether or not vPEs are
> > + * allocated for the VM.
> > + */
> > + if (system_supports_direct_sgis() && !vgic_supports_direct_sgis(kvm))
> > + return false;
> > +
> > return kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm);
> > }
> >
> > diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
> > index 1384a04c0784..de1c1d3261c3 100644
> > --- a/arch/arm64/kvm/vgic/vgic.h
> > +++ b/arch/arm64/kvm/vgic/vgic.h
> > @@ -396,15 +396,7 @@ bool vgic_supports_direct_sgis(struct kvm *kvm);
> >
> > static inline bool vgic_supports_direct_irqs(struct kvm *kvm)
> > {
> > - /*
> > - * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware,
> > - * indirectly allowing userspace to control whether or not vPEs are
> > - * allocated for the VM.
> > - */
> > - if (system_supports_direct_sgis())
> > - return vgic_supports_direct_sgis(kvm);
> > -
> > - return vgic_supports_direct_msis(kvm);
> > + return vgic_supports_direct_msis(kvm) || vgic_supports_direct_sgis(kvm);
> > }
> >
> > int vgic_v4_init(struct kvm *kvm);
>
> Yes, the diff seems fine (tested as well). Would you be pushing a v2
> or do you want me to (on your behalf)?
Go ahead and respin this diff, thanks!
Oliver
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2025-07-29 18:05 UTC | newest]
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2025-07-28 22:37 [PATCH] KVM: arm64: Set/unset vGIC v4 forwarding if direct IRQs are supported Raghavendra Rao Ananta
2025-07-29 14:37 ` Oliver Upton
2025-07-29 16:56 ` Raghavendra Rao Ananta
2025-07-29 18:02 ` Oliver Upton
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