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Date:   Wed, 2 Nov 2022 15:46:31 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     Jinank Jain <jinankjain@linux.microsoft.com>
Cc:     kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com,
        wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de,
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        x86@kernel.org, hpa@zytor.com, arnd@arndb.de, peterz@infradead.org,
        jpoimboe@kernel.org, seanjc@google.com,
        kirill.shutemov@linux.intel.com, ak@linux.intel.com,
        sathyanarayanan.kuppuswamy@linux.intel.com,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org
Subject: Re: [PATCH 6/6] hv, mshv : Change interrupt vector for nested root
 partition
Message-ID: <Y2KQ1w5GOd/PcN61@liuwe-devbox-debian-v2>
References: <cover.1667394408.git.jinankjain@microsoft.com>
 <22b6428cc90efb4ed970d61249c877b373a7002a.1667394408.git.jinankjain@microsoft.com>
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On Wed, Nov 02, 2022 at 02:00:17PM +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@linux.microsoft.com>
> ---
>  arch/x86/include/asm/idtentry.h    |  2 ++
>  arch/x86/include/asm/irq_vectors.h |  6 ++++++
[...]
>  #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

I would like to hear x86 maintainers opinion on this.

Thanks,
Wei.