From 2113c5f62b7423e4a72b890bd479704aa85c81ba Mon Sep 17 00:00:00 2001 From: Andrew Jones Date: Thu, 22 Aug 2019 13:03:05 +0200 Subject: KVM: arm/arm64: Only skip MMIO insn once If after an MMIO exit to userspace a VCPU is immediately run with an immediate_exit request, such as when a signal is delivered or an MMIO emulation completion is needed, then the VCPU completes the MMIO emulation and immediately returns to userspace. As the exit_reason does not get changed from KVM_EXIT_MMIO in these cases we have to be careful not to complete the MMIO emulation again, when the VCPU is eventually run again, because the emulation does an instruction skip (and doing too many skips would be a waste of guest code :-) We need to use additional VCPU state to track if the emulation is complete. As luck would have it, we already have 'mmio_needed', which even appears to be used in this way by other architectures already. Fixes: 0d640732dbeb ("arm64: KVM: Skip MMIO insn after emulation") Acked-by: Mark Rutland Signed-off-by: Andrew Jones Signed-off-by: Marc Zyngier --- virt/kvm/arm/mmio.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'virt') diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c index a8a6a0c883f1..6af5c91337f2 100644 --- a/virt/kvm/arm/mmio.c +++ b/virt/kvm/arm/mmio.c @@ -86,6 +86,12 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) unsigned int len; int mask; + /* Detect an already handled MMIO return */ + if (unlikely(!vcpu->mmio_needed)) + return 0; + + vcpu->mmio_needed = 0; + if (!run->mmio.is_write) { len = run->mmio.len; if (len > sizeof(unsigned long)) @@ -188,6 +194,7 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, run->mmio.is_write = is_write; run->mmio.phys_addr = fault_ipa; run->mmio.len = len; + vcpu->mmio_needed = 1; if (!ret) { /* We handled the access successfully in the kernel. */ -- cgit From 2e16f3e926ed48373c98edea85c6ad0ef69425d1 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Fri, 23 Aug 2019 11:34:16 +0100 Subject: KVM: arm/arm64: VGIC: Properly initialise private IRQ affinity At the moment we initialise the target *mask* of a virtual IRQ to the VCPU it belongs to, even though this mask is only defined for GICv2 and quickly runs out of bits for many GICv3 guests. This behaviour triggers an UBSAN complaint for more than 32 VCPUs: ------ [ 5659.462377] UBSAN: Undefined behaviour in virt/kvm/arm/vgic/vgic-init.c:223:21 [ 5659.471689] shift exponent 32 is too large for 32-bit type 'unsigned int' ------ Also for GICv3 guests the reporting of TARGET in the "vgic-state" debugfs dump is wrong, due to this very same problem. Because there is no requirement to create the VGIC device before the VCPUs (and QEMU actually does it the other way round), we can't safely initialise mpidr or targets in kvm_vgic_vcpu_init(). But since we touch every private IRQ for each VCPU anyway later (in vgic_init()), we can just move the initialisation of those fields into there, where we definitely know the VGIC type. On the way make sure we really have either a VGICv2 or a VGICv3 device, since the existing code is just checking for "VGICv3 or not", silently ignoring the uninitialised case. Signed-off-by: Andre Przywara Reported-by: Dave Martin Tested-by: Julien Grall Signed-off-by: Marc Zyngier --- virt/kvm/arm/vgic/vgic-init.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) (limited to 'virt') diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c index bdbc297d06fb..e621b5d45b27 100644 --- a/virt/kvm/arm/vgic/vgic-init.c +++ b/virt/kvm/arm/vgic/vgic-init.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include "vgic.h" @@ -164,12 +165,18 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis) irq->vcpu = NULL; irq->target_vcpu = vcpu0; kref_init(&irq->refcount); - if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V2) { + switch (dist->vgic_model) { + case KVM_DEV_TYPE_ARM_VGIC_V2: irq->targets = 0; irq->group = 0; - } else { + break; + case KVM_DEV_TYPE_ARM_VGIC_V3: irq->mpidr = 0; irq->group = 1; + break; + default: + kfree(dist->spis); + return -EINVAL; } } return 0; @@ -209,7 +216,6 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu) irq->intid = i; irq->vcpu = NULL; irq->target_vcpu = vcpu; - irq->targets = 1U << vcpu->vcpu_id; kref_init(&irq->refcount); if (vgic_irq_is_sgi(i)) { /* SGIs */ @@ -219,11 +225,6 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu) /* PPIs */ irq->config = VGIC_CONFIG_LEVEL; } - - if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) - irq->group = 1; - else - irq->group = 0; } if (!irqchip_in_kernel(vcpu->kvm)) @@ -286,10 +287,19 @@ int vgic_init(struct kvm *kvm) for (i = 0; i < VGIC_NR_PRIVATE_IRQS; i++) { struct vgic_irq *irq = &vgic_cpu->private_irqs[i]; - if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) + switch (dist->vgic_model) { + case KVM_DEV_TYPE_ARM_VGIC_V3: irq->group = 1; - else + irq->mpidr = kvm_vcpu_get_mpidr_aff(vcpu); + break; + case KVM_DEV_TYPE_ARM_VGIC_V2: irq->group = 0; + irq->targets = 1U << idx; + break; + default: + ret = -EINVAL; + goto out; + } } } -- cgit