Gregory Haskins wrote:
> From: None <None>
>
> The current code is geared towards using a user-mode (A)PIC. This patch adds
> an "irqdevice" abstraction, and implements a "userint" model to handle the
> duties of the original code. Later, we can develop other irqdevice models
> to handle objects like LAPIC, IOAPIC, i8259, etc, as appropriate
>
>
Viewed in light of 3/3, various races are exposed.
> @@ -2044,13 +2043,11 @@ static int kvm_vcpu_ioctl_set_sregs(struct kvm_vcpu
> *vcpu,
> if (mmu_reset_needed)
> kvm_mmu_reset_context(vcpu);
>
> - memcpy(vcpu->irq_pending, sregs->interrupt_bitmap,
> - sizeof vcpu->irq_pending);
> - vcpu->irq_summary = 0;
> - for (i = 0; i < NR_IRQ_WORDS; ++i)
> - if (vcpu->irq_pending[i])
> - __set_bit(i, &vcpu->irq_summary);
> -
> + /* walk the interrupt-bitmap and inject an IRQ for each bit found */
> + for (i = 0; i < 256; ++i)
> + if (test_bit(i, &sregs->interrupt_bitmap[0]))
> + kvm_irqdevice_set_pin(&vcpu->irq_dev, i, 1);
> +
>
You need to lower a pin here if it was previously set.
> diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
> index 61a6116..a0fdf02 100644
> --- a/drivers/kvm/vmx.c
> +++ b/drivers/kvm/vmx.c
> @@ -1219,13 +1219,8 @@ static void inject_rmode_irq(struct kvm_vcpu *vcpu,
> int irq)
>
> static void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
> {
> - int word_index = __ffs(vcpu->irq_summary);
> - int bit_index = __ffs(vcpu->irq_pending[word_index]);
> - int irq = word_index * BITS_PER_LONG + bit_index;
> -
> - clear_bit(bit_index, &vcpu->irq_pending[word_index]);
> - if (!vcpu->irq_pending[word_index])
> - clear_bit(word_index, &vcpu->irq_summary);
> + int irq = kvm_irqdevice_read_vector(&vcpu->irq_dev, 0);
> + BUG_ON(irq < 0);
>
This BUG can trigger. A level-triggered irq was asserted, then deasserted.
>
> if (vcpu->rmode.active) {
> inject_rmode_irq(vcpu, irq);
> @@ -1246,7 +1241,7 @@ static void do_interrupt_requests(struct kvm_vcpu *vcpu,
> (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0);
>
> if (vcpu->interrupt_window_open &&
> - vcpu->irq_summary &&
> + kvm_irqdevice_pending(&vcpu->irq_dev, 0) &&
> !(vmcs_read32(VM_ENTRY_INTR_INFO_FIELD) & INTR_INFO_VALID_MASK))
>
What if an irq is made pending here?
> /*
> * If interrupts enabled, and not blocked by sti or mov ss.
> Good.
> @@ -1255,7 +1250,8 @@ static void do_interrupt_requests(struct kvm_vcpu *vcpu,
>
> cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
> if (!vcpu->interrupt_window_open &&
> - (vcpu->irq_summary || kvm_run->request_interrupt_window))
> + (kvm_irqdevice_pending(&vcpu->irq_dev, 0) ||
> + kvm_run->request_interrupt_window))
> /*
> * Interrupts blocked. Wait for unblock.
> */
>
or here?
> @@ -1619,8 +1615,9 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
> kvm_run->if_flag = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) != 0;
> kvm_run->cr8 = vcpu->cr8;
> kvm_run->apic_base = vcpu->apic_base;
> - kvm_run->ready_for_interrupt_injection = (vcpu->interrupt_window_open &&
> - vcpu->irq_summary == 0);
> + kvm_run->ready_for_interrupt_injection =
> + (vcpu->interrupt_window_open &&
> + !kvm_irqdevice_pending(&vcpu->irq_dev, 0));
> }
>
or here? possibly a good answer is "don't rely on r_f_i_i if not using
userint".
>
> static int handle_interrupt_window(struct kvm_vcpu *vcpu,
> @@ -1631,7 +1628,7 @@ static int handle_interrupt_window(struct kvm_vcpu
> *vcpu,
> * possible
> */
> if (kvm_run->request_interrupt_window &&
> - !vcpu->irq_summary) {
> + !kvm_irqdevice_pending(&vcpu->irq_dev, 0)) {
> kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
> ++kvm_stat.irq_window_exits;
> return 0;
>
ditto.
> @@ -1713,7 +1710,7 @@ static int kvm_handle_exit(struct kvm_run *kvm_run,
> struct kvm_vcpu *vcpu)
> static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu,
> struct kvm_run *kvm_run)
> {
> - return (!vcpu->irq_summary &&
> + return (!kvm_irqdevice_pending(&vcpu->irq_dev, 0) &&
> kvm_run->request_interrupt_window &&
> vcpu->interrupt_window_open &&
> (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF));
>
>
>
ditto.
--
error compiling committee.c: too many arguments to function
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