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Message-ID: <a56e499f-c91c-45da-b404-444c22b2df24@redhat.com>
Date:   Mon, 30 Oct 2023 18:36:07 +0100
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Subject: Re: [PATCH v13 23/35] KVM: x86: Add support for "protected VMs" that
 can utilize private memory
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To:     Sean Christopherson <seanjc@google.com>,
        Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        Huacai Chen <chenhuacai@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Anup Patel <anup@brainfault.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        kvmarm@lists.linux.dev, linux-mips@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org,
        linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Xiaoyao Li <xiaoyao.li@intel.com>,
        Xu Yilun <yilun.xu@intel.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Fuad Tabba <tabba@google.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Anish Moorthy <amoorthy@google.com>,
        David Matlack <dmatlack@google.com>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Isaku Yamahata <isaku.yamahata@intel.com>,
        =?UTF-8?B?TWlja2HDq2wgU2FsYcO8?= =?UTF-8?Q?n?= <mic@digikod.net>,
        Vlastimil Babka <vbabka@suse.cz>,
        Vishal Annapurve <vannapurve@google.com>,
        Ackerley Tng <ackerleytng@google.com>,
        Maciej Szmigiero <mail@maciej.szmigiero.name>,
        David Hildenbrand <david@redhat.com>,
        Quentin Perret <qperret@google.com>,
        Michael Roth <michael.roth@amd.com>,
        Wang <wei.w.wang@intel.com>,
        Liam Merwick <liam.merwick@oracle.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
References: <20231027182217.3615211-1-seanjc@google.com>
 <20231027182217.3615211-24-seanjc@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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In-Reply-To: <20231027182217.3615211-24-seanjc@google.com>
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On 10/27/23 20:22, Sean Christopherson wrote:
> Add a new x86 VM type, KVM_X86_SW_PROTECTED_VM, to serve as a development
> and testing vehicle for Confidential (CoCo) VMs, and potentially to even
> become a "real" product in the distant future, e.g. a la pKVM.
> 
> The private memory support in KVM x86 is aimed at AMD's SEV-SNP and
> Intel's TDX, but those technologies are extremely complex (understatement),
> difficult to debug, don't support running as nested guests, and require
> hardware that's isn't universally accessible.  I.e. relying SEV-SNP or TDX
> for maintaining guest private memory isn't a realistic option.
> 
> At the very least, KVM_X86_SW_PROTECTED_VM will enable a variety of
> selftests for guest_memfd and private memory support without requiring
> unique hardware.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

with one nit:

> +---------------------
> +
> +:Capability: KVM_CAP_MEMORY_ATTRIBUTES
> +:Architectures: x86
> +:Type: system ioctl
> +
> +This capability returns a bitmap of support VM types.  The 1-setting of bit @n

s/support/supported/

Paolo