On Mon, Jan 02, 2023 at 07:12:55AM +0000, Jinank Jain wrote:
> Traditionally we have been using the HYPERVISOR_CALLBACK_VECTOR to relay
> the VMBus interrupt. But this does not work in case of nested
> hypervisor. Microsoft Hypervisor reserves 0x31 to 0x34 as the interrupt
> vector range for VMBus and thus we have to use one of the vectors from
> that range and setup the IDT accordingly.
>
> Signed-off-by: Jinank Jain <jinankjain@xxxxxxxxxxxxxxxxxxx>
I've applied all but this patch to hyperv-next.
This patch still needs an ack or nack from x86 maintainers to proceed.
Thanks,
Wei.
> ---
> arch/x86/include/asm/idtentry.h | 2 ++
> arch/x86/include/asm/irq_vectors.h | 6 ++++++
> arch/x86/kernel/cpu/mshyperv.c | 15 +++++++++++++++
> arch/x86/kernel/idt.c | 10 ++++++++++
> drivers/hv/vmbus_drv.c | 3 ++-
> 5 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
> index 72184b0b2219..c0648e3e4d4a 100644
> --- a/arch/x86/include/asm/idtentry.h
> +++ b/arch/x86/include/asm/idtentry.h
> @@ -686,6 +686,8 @@ DECLARE_IDTENTRY_SYSVEC(POSTED_INTR_NESTED_VECTOR, sysvec_kvm_posted_intr_nested
> DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR, sysvec_hyperv_callback);
> DECLARE_IDTENTRY_SYSVEC(HYPERV_REENLIGHTENMENT_VECTOR, sysvec_hyperv_reenlightenment);
> DECLARE_IDTENTRY_SYSVEC(HYPERV_STIMER0_VECTOR, sysvec_hyperv_stimer0);
> +DECLARE_IDTENTRY_SYSVEC(HYPERV_INTR_NESTED_VMBUS_VECTOR,
> + sysvec_hyperv_nested_vmbus_intr);
> #endif
>
> #if IS_ENABLED(CONFIG_ACRN_GUEST)
> diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
> index 43dcb9284208..729d19eab7f5 100644
> --- a/arch/x86/include/asm/irq_vectors.h
> +++ b/arch/x86/include/asm/irq_vectors.h
> @@ -102,6 +102,12 @@
> #if IS_ENABLED(CONFIG_HYPERV)
> #define HYPERV_REENLIGHTENMENT_VECTOR 0xee
> #define HYPERV_STIMER0_VECTOR 0xed
> +/*
> + * FIXME: Change this, once Microsoft Hypervisor changes its assumption
> + * around VMBus interrupt vector allocation for nested root partition.
> + * Or provides a better interface to detect this instead of hardcoding.
> + */
> +#define HYPERV_INTR_NESTED_VMBUS_VECTOR 0x31
> #endif
>
> #define LOCAL_TIMER_VECTOR 0xec
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 938fc82edf05..4dfe0f9d7be3 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -126,6 +126,21 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
> set_irq_regs(old_regs);
> }
>
> +DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_nested_vmbus_intr)
> +{
> + struct pt_regs *old_regs = set_irq_regs(regs);
> +
> + inc_irq_stat(irq_hv_callback_count);
> +
> + if (vmbus_handler)
> + vmbus_handler();
> +
> + if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
> + ack_APIC_irq();
> +
> + set_irq_regs(old_regs);
> +}
> +
> void hv_setup_vmbus_handler(void (*handler)(void))
> {
> vmbus_handler = handler;
> diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
> index a58c6bc1cd68..3536935cea39 100644
> --- a/arch/x86/kernel/idt.c
> +++ b/arch/x86/kernel/idt.c
> @@ -160,6 +160,16 @@ static const __initconst struct idt_data apic_idts[] = {
> # endif
> INTG(SPURIOUS_APIC_VECTOR, asm_sysvec_spurious_apic_interrupt),
> INTG(ERROR_APIC_VECTOR, asm_sysvec_error_interrupt),
> +#ifdef CONFIG_HYPERV
> + /*
> + * This is a hack because we cannot install this interrupt handler
> + * via alloc_intr_gate as it does not allow interrupt vector less
> + * than FIRST_SYSTEM_VECTORS. And hyperv does not want anything other
> + * than 0x31-0x34 as the interrupt vector for vmbus interrupt in case
> + * of nested setup.
> + */
> + INTG(HYPERV_INTR_NESTED_VMBUS_VECTOR, asm_sysvec_hyperv_nested_vmbus_intr),
> +#endif
> #endif
> };
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 6324e01d5eec..740878367426 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -2768,7 +2768,8 @@ static int __init hv_acpi_init(void)
> * normal Linux IRQ mechanism is not used in this case.
> */
> #ifdef HYPERVISOR_CALLBACK_VECTOR
> - vmbus_interrupt = HYPERVISOR_CALLBACK_VECTOR;
> + vmbus_interrupt = hv_nested ? HYPERV_INTR_NESTED_VMBUS_VECTOR :
> + HYPERVISOR_CALLBACK_VECTOR;
> vmbus_irq = -1;
> #endif
>
> --
> 2.25.1
>
