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| author | Yi Wang <foxywang@tencent.com> | 2024-05-06 18:17:49 +0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-06-11 14:18:34 -0700 |
| commit | fbe4a7e881d4408bfabbb4fd538f10fd686cd8ab (patch) | |
| tree | 104d9dd3cfe88d4f5b9a9c713f483aecf9d6bcd0 /virt | |
| parent | f2362c04752ca23ee65d476795f4e2ea444f1809 (diff) | |
| download | linux-fbe4a7e881d4408bfabbb4fd538f10fd686cd8ab.tar.gz linux-fbe4a7e881d4408bfabbb4fd538f10fd686cd8ab.tar.bz2 linux-fbe4a7e881d4408bfabbb4fd538f10fd686cd8ab.zip | |
KVM: Setup empty IRQ routing when creating a VM
Setup empty IRQ routing during VM creation so that x86 and s390 don't need
to set empty/dummy IRQ routing during KVM_CREATE_IRQCHIP (in future
patches). Initializing IRQ routing before there are any potential readers
allows KVM to avoid the synchronize_srcu() in kvm_set_irq_routing(), which
can introduces 20+ milliseconds of latency in the VM creation path.
Ensuring that all VMs have non-NULL IRQ routing also hardens KVM against
misbehaving userspace VMMs, e.g. RISC-V dynamically instantiates its
interrupt controller, but doesn't override kvm_arch_intc_initialized() or
kvm_arch_irqfd_allowed(), and so can likely reach kvm_irq_map_gsi()
without fully initialized IRQ routing.
Signed-off-by: Yi Wang <foxywang@tencent.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20240506101751.3145407-2-foxywang@tencent.com
[sean: init refcount after IRQ routing, fix stub, massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/irqchip.c | 24 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 7 |
2 files changed, 31 insertions, 0 deletions
diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c index 1e567d1f6d3d..162d8ed889f2 100644 --- a/virt/kvm/irqchip.c +++ b/virt/kvm/irqchip.c @@ -237,3 +237,27 @@ out: return r; } + +/* + * Allocate empty IRQ routing by default so that additional setup isn't needed + * when userspace-driven IRQ routing is activated, and so that kvm->irq_routing + * is guaranteed to be non-NULL. + */ +int kvm_init_irq_routing(struct kvm *kvm) +{ + struct kvm_irq_routing_table *new; + int chip_size; + + new = kzalloc(struct_size(new, map, 1), GFP_KERNEL_ACCOUNT); + if (!new) + return -ENOMEM; + + new->nr_rt_entries = 1; + + chip_size = sizeof(int) * KVM_NR_IRQCHIPS * KVM_IRQCHIP_NUM_PINS; + memset(new->chip, -1, chip_size); + + RCU_INIT_POINTER(kvm->irq_routing, new); + + return 0; +} diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index f4f5a435b225..7bf1ef0fc10b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1186,7 +1186,12 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) if (init_srcu_struct(&kvm->irq_srcu)) goto out_err_no_irq_srcu; + r = kvm_init_irq_routing(kvm); + if (r) + goto out_err_no_irq_routing; + refcount_set(&kvm->users_count, 1); + for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { for (j = 0; j < 2; j++) { slots = &kvm->__memslots[i][j]; @@ -1265,6 +1270,8 @@ out_err_no_arch_destroy_vm: WARN_ON_ONCE(!refcount_dec_and_test(&kvm->users_count)); for (i = 0; i < KVM_NR_BUSES; i++) kfree(kvm_get_bus(kvm, i)); + kvm_free_irq_routing(kvm); +out_err_no_irq_routing: cleanup_srcu_struct(&kvm->irq_srcu); out_err_no_irq_srcu: cleanup_srcu_struct(&kvm->srcu); |