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AJvYcCXUk41dyedjXkTPvyxlTziHWw/MOl4Zki4zzuZi6BJNwkyvGCO8zZxeAUCJujYBfS3Nzx58RbU=@lists.linux.dev X-Gm-Message-State: AOJu0Yw7HX7VL8VZiOjhqVUl00c++Za1KLHFc8BkE/8AWMyC77L5bLwh AxX4dlAkzlo5ebmIYBNlrb/5Wyr5jO+QHBZ17a8isXno2Y8FA9tv2LCE8f1LRbF/7wH4iXw+mzq Q1A== X-Google-Smtp-Source: AGHT+IFPeiRjT/hk2eJKjjXIwZ7MAsw5CZ9JjPkhCk3imTKy+4sECTwl7nHXrtoS7dfr9P6aVkCK1zl5Ww== X-Received: from wmbha11.prod.google.com ([2002:a05:600c:860b:b0:453:b96:8ef9]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:3c9:b0:3a4:f787:9b58 with SMTP id ffacd0b85a97d-3b5e454249emr1500559f8f.58.1752058811734; Wed, 09 Jul 2025 04:00:11 -0700 (PDT) Date: Wed, 9 Jul 2025 11:59:37 +0100 In-Reply-To: <20250709105946.4009897-1-tabba@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250709105946.4009897-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250709105946.4009897-12-tabba@google.com> Subject: [PATCH v13 11/20] KVM: x86/mmu: Allow NULL-able fault in kvm_max_private_mapping_level From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev 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, tabba@google.com Content-Type: text/plain; charset="UTF-8" From: Ackerley Tng Refactor kvm_max_private_mapping_level() to accept a NULL kvm_page_fault pointer and rename it to kvm_gmem_max_mapping_level(). The max_mapping_level x86 operation (previously private_max_mapping_level) is designed to potentially be called without an active page fault, for instance, when kvm_mmu_max_mapping_level() is determining the maximum mapping level for a gfn proactively. Allow NULL fault pointer: Modify kvm_max_private_mapping_level() to safely handle a NULL fault argument. This aligns its interface with the kvm_x86_ops.max_mapping_level operation it wraps, which can also be called with NULL. Rename function to kvm_gmem_max_mapping_level(): This reinforces that the function's scope is for guest_memfd-backed memory, which can be either private or non-private, removing any remaining "private" connotation from its name. Optimize max_level checks: Introduce a check in the caller to skip querying for max_mapping_level if the current max_level is already PG_LEVEL_4K, as no further reduction is possible. Suggested-by: Sean Christoperson Signed-off-by: Ackerley Tng Signed-off-by: Fuad Tabba --- arch/x86/kvm/mmu/mmu.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index bb925994cbc5..495dcedaeafa 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4467,17 +4467,13 @@ static inline u8 kvm_max_level_for_order(int order) return PG_LEVEL_4K; } -static u8 kvm_max_private_mapping_level(struct kvm *kvm, - struct kvm_page_fault *fault, - int gmem_order) +static u8 kvm_gmem_max_mapping_level(struct kvm *kvm, int order, + struct kvm_page_fault *fault) { - u8 max_level = fault->max_level; u8 req_max_level; + u8 max_level; - if (max_level == PG_LEVEL_4K) - return PG_LEVEL_4K; - - max_level = min(kvm_max_level_for_order(gmem_order), max_level); + max_level = kvm_max_level_for_order(order); if (max_level == PG_LEVEL_4K) return PG_LEVEL_4K; @@ -4513,7 +4509,10 @@ static int kvm_mmu_faultin_pfn_private(struct kvm_vcpu *vcpu, } fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY); - fault->max_level = kvm_max_private_mapping_level(vcpu->kvm, fault, max_order); + if (fault->max_level >= PG_LEVEL_4K) { + fault->max_level = kvm_gmem_max_mapping_level(vcpu->kvm, + max_order, fault); + } return RET_PF_CONTINUE; } -- 2.50.0.727.gbf7dc18ff4-goog