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Message-ID: <70acccee-22d7-0d35-b943-346a435b9eab@quicinc.com>
Date:   Fri, 28 Apr 2023 15:48:33 -0700
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Subject: Re: [PATCH v2 3/7] virt: geniezone: Introduce GenieZone hypervisor
 support
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To:     Marc Zyngier <maz@kernel.org>, Yi-De Wu <yi-de.wu@mediatek.com>
CC:     Yingshiuan Pan <yingshiuan.pan@mediatek.com>,
        Ze-Yu Wang <ze-yu.wang@mediatek.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-doc@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-arch@vger.kernel.org>, <linux-mediatek@lists.infradead.org>,
        David Bradil <dbrazdil@google.com>,
        Jade Shih <jades.shih@mediatek.com>,
        Miles Chen <miles.chen@mediatek.com>,
        Ivan Tseng <ivan.tseng@mediatek.com>,
        My Chuang <my.chuang@mediatek.com>,
        Shawn Hsiao <shawn.hsiao@mediatek.com>,
        PeiLun Suei <peilun.suei@mediatek.com>,
        Liju Chen <liju-clr.chen@mediatek.com>
References: <20230428103622.18291-1-yi-de.wu@mediatek.com>
 <20230428103622.18291-4-yi-de.wu@mediatek.com>
 <904abf67ec4ba7d37fc1e500e8a2dbd1@kernel.org>
From:   Trilok Soni <quic_tsoni@quicinc.com>
In-Reply-To: <904abf67ec4ba7d37fc1e500e8a2dbd1@kernel.org>
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Hi Marc,

> 
> [...]
> 
>> +/**
>> + * gzvm_gfn_to_pfn_memslot() - Translate gfn (guest ipa) to pfn (host 
>> pa),
>> + *                   result is in @pfn
>> + *
>> + * Leverage KVM's gfn_to_pfn_memslot(). Because gfn_to_pfn_memslot() 
>> needs
>> + * kvm_memory_slot as parameter, this function populates necessary 
>> fileds
>> + * for calling gfn_to_pfn_memslot().
>> + *
>> + * Return:
>> + * * 0            - Succeed
>> + * * -EFAULT        - Failed to convert
>> + */
>> +static int gzvm_gfn_to_pfn_memslot(struct gzvm_memslot *memslot, u64
>> gfn, u64 *pfn)
>> +{
>> +    hfn_t __pfn;
>> +    struct kvm_memory_slot kvm_slot = {0};
>> +
>> +    kvm_slot.base_gfn = memslot->base_gfn;
>> +    kvm_slot.npages = memslot->npages;
>> +    kvm_slot.dirty_bitmap = NULL;
>> +    kvm_slot.userspace_addr = memslot->userspace_addr;
>> +    kvm_slot.flags = memslot->flags;
>> +    kvm_slot.id = memslot->slot_id;
>> +    kvm_slot.as_id = 0;
>> +
>> +    __pfn = gfn_to_pfn_memslot(&kvm_slot, gfn);
> 
> Again, I absolutely oppose this horror. This is internal to KVM,
> and we want to be able to change this without having to mess
> with your own code that we cannot test anyway.
> 
> What if we start using the extra fields that you don't populate
> as they mean nothing to you? Or add a backpointer to the kvm
> structure to do fancy accounting?
> 
> You have your own hypervisor, that's well and good. Since your
> main argument is that it is supposed to be standalone, make it
> *really* standalone and don't use KVM as a prop.


Agreed, same comments were made earlier too. I would prefer that 
GenieZone have its own identify rather than sharing the 
APIs/data-structures here.

---Trilok Soni