From: Raghavendra Rao Ananta Date: Tue, 29 Jul 2025 21:06:44 +0000 (+0000) Subject: KVM: arm64: Don't attempt vLPI mappings when vPE allocation is disabled X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7b8346bd9fce6b76a96c6780d2e5bba76687f97f;p=users%2Fjedix%2Flinux-maple.git KVM: arm64: Don't attempt vLPI mappings when vPE allocation is disabled commit c652887a9288 ("KVM: arm64: vgic-v3: Allow userspace to write GICD_TYPER2.nASSGIcap") makes the allocation of vPEs depend on nASSGIcap for GICv4.1 hosts. While the vGIC v4 initialization and teardown is handled correctly, it erroneously attempts to establish a vLPI mapping to a VM that has no vPEs allocated: 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 it by moving the GICv4.1 special-casing to vgic_supports_direct_msis(), returning false if the user explicitly disabled nASSGIcap for the VM. Fixes: c652887a9288 ("KVM: arm64: vgic-v3: Allow userspace to write GICD_TYPER2.nASSGIcap") Suggested-by: Oliver Upton Signed-off-by: Raghavendra Rao Ananta Link: https://lore.kernel.org/r/20250729210644.830364-1-rananta@google.com Signed-off-by: Oliver Upton --- diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c index a3ef185209e99..70d50c77e5dc7 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 1384a04c07848..de1c1d3261c39 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);