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Thu, 15 May 2025 16:42:54 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFRL/1O/Rrnq8ioMs+d0i5/D3GPpfrLPajlUsLeikruv+Yje3p8yvM4Ix2Eud3DGPaH1u34zA== X-Received: by 2002:a17:90b:3e8e:b0:2ff:58e1:2bb1 with SMTP id 98e67ed59e1d1-30e7d5bb1e9mr1333477a91.32.1747352574064; Thu, 15 May 2025 16:42:54 -0700 (PDT) Received: from [192.168.68.51] ([180.233.125.65]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-30e334016e7sm4069046a91.9.2025.05.15.16.42.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 May 2025 16:42:53 -0700 (PDT) Message-ID: <9a2431e0-252d-41c9-a91d-9e02a8779e8c@redhat.com> Date: Fri, 16 May 2025 09:42:31 +1000 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 07/17] KVM: guest_memfd: Allow host to map guest_memfd() pages To: Fuad Tabba , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com References: <20250513163438.3942405-1-tabba@google.com> <20250513163438.3942405-8-tabba@google.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20250513163438.3942405-8-tabba@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Fuad, On 5/14/25 2:34 AM, Fuad Tabba wrote: > This patch enables support for shared memory in guest_memfd, including > mapping that memory at the host userspace. This support is gated by the > configuration option KVM_GMEM_SHARED_MEM, and toggled by the guest_memfd > flag GUEST_MEMFD_FLAG_SUPPORT_SHARED, which can be set when creating a > guest_memfd instance. > > Co-developed-by: Ackerley Tng > Signed-off-by: Ackerley Tng > Signed-off-by: Fuad Tabba > --- > arch/x86/include/asm/kvm_host.h | 10 ++++ > include/linux/kvm_host.h | 13 +++++ > include/uapi/linux/kvm.h | 1 + > virt/kvm/Kconfig | 5 ++ > virt/kvm/guest_memfd.c | 88 +++++++++++++++++++++++++++++++++ > 5 files changed, 117 insertions(+) > [...] > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index b6ae8ad8934b..9857022a0f0c 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1566,6 +1566,7 @@ struct kvm_memory_attributes { > #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) > > #define KVM_CREATE_GUEST_MEMFD _IOWR(KVMIO, 0xd4, struct kvm_create_guest_memfd) > +#define GUEST_MEMFD_FLAG_SUPPORT_SHARED (1UL << 0) > This would be (1ULL << 0) to be consistent with '__u64 struct kvm_create_guest_memfd::flags' Thanks, Gavin