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AJvYcCWls+f/W5mmeV9oUJSmmg3ay0qI7w9602leYWoyV/FCoaGUIBZBN0cqRvTgbQ4fMOiXUxDqtZrsCg==@kvack.org X-Gm-Message-State: AOJu0Yxd4tv8EYG7ge8sGKZGii0OLf/1Qhix0HehE7vbtqqR9l/qWGzJ B9p5RLJSxRuYqJPqqYEl1GehgRjZqQg4fuuGv2j817fzdGuLdyJhCTVZnF1dWoAXj/XlsaVocZP png== X-Google-Smtp-Source: AGHT+IEDLe189qOiRgDedu5bKfhg6mmUJkhqiiy6MmhlJTVyAYMWtzw6N/Xpnr+zd4xHJ/TAYV4yM5jmtg== X-Received: from edbev26.prod.google.com ([2002:a05:6402:541a:b0:609:287d:ce97]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:22ba:b0:607:7de4:598b with SMTP id 4fb4d7f45d1cf-611e7636978mr9326687a12.9.1752572055050; Tue, 15 Jul 2025 02:34:15 -0700 (PDT) Date: Tue, 15 Jul 2025 10:33:40 +0100 In-Reply-To: <20250715093350.2584932-1-tabba@google.com> Mime-Version: 1.0 References: <20250715093350.2584932-1-tabba@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250715093350.2584932-12-tabba@google.com> Subject: [PATCH v14 11/21] 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" X-Rspamd-Queue-Id: 8F887160007 X-Stat-Signature: opgdf3t3418i6my798aznudwg3zjdcqf X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1752572056-346282 X-HE-Meta: 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 vSKH0VzS fHZ8GJ4Bwi6ObcFPI7sgLO9nm5kdMCVWOr4VW/DvUHvpvlbbnUc3jCNFlOt8o0xD7kCZEUW56JtzCAh9A4tI3ui4HaCW1qQ+wFoFk8rzsvggT0zfbnDcVf6WBGeGv20ylDCwJWvaSVE/1IlfT3sPPzXhhrSJ/bF8EeB6+0SXL8iwsCWOgik0Or9rVyyPQJ0yl7dWB9bQydzSREMLZYX15gfbIZstBgb0nGjjILeKnNA7gHb1weZ8c4N60UnPkwgVkt7Y+w3ImiY+PZFPu2fYpj6zh70Rh0hKrC8ovTE0Irena/Qz8xwTSO9u38t5gEmZtqlfeTuqY9GipQMug4Rfh0BHnpOcfC9M9Gk3yuGQxqT/DPLb6V32FC5rMRg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Acked-by: David Hildenbrand Suggested-by: Sean Christoperson Signed-off-by: Ackerley Tng Signed-off-by: Fuad Tabba --- arch/x86/kvm/mmu/mmu.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index bb925994cbc5..6bd28fda0fd3 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 +4509,9 @@ 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