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Fri, 06 Dec 2024 14:46:59 -0800 (PST) Date: Fri, 6 Dec 2024 22:46:58 +0000 In-Reply-To: <202412052133.pTg3UAQm-lkp@intel.com> Mime-Version: 1.0 References: <202412052133.pTg3UAQm-lkp@intel.com> X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241206224658.2833655-1-jthoughton@google.com> Subject: Re: [PATCH v1 01/13] KVM: Add KVM_MEM_USERFAULT memslot flag and bitmap From: James Houghton To: lkp@intel.com Cc: amoorthy@google.com, corbet@lwn.net, dmatlack@google.com, jthoughton@google.com, kalyazin@amazon.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, maz@kernel.org, oe-kbuild-all@lists.linux.dev, oliver.upton@linux.dev, pbonzini@redhat.com, peterx@redhat.com, pgonda@google.com, seanjc@google.com, wei.w.wang@intel.com, yan.y.zhao@intel.com Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241206_144701_356099_9CE71CEA X-CRM114-Status: GOOD ( 10.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_set_memory_region': > >> arch/x86/kvm/../../../virt/kvm/kvm_main.c:2049:41: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] > 2049 | new->userfault_bitmap = (unsigned long *)mem->userfault_bitmap; > | ^ I realize that, not only have I done this cast slightly wrong, I'm missing a few checks on userfault_bitmap that I should have. Applying this diff, or at least something like it, to fix it: diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b552cdef2850..30f09141df64 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1977,6 +1977,12 @@ int __kvm_set_memory_region(struct kvm *kvm, return -EINVAL; if ((mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES) return -EINVAL; + if (mem->flags & KVM_MEM_USERFAULT && + ((mem->userfault_bitmap != untagged_addr(mem->userfault_bitmap)) || + !access_ok((void __user *)(unsigned long)mem->userfault_bitmap, + DIV_ROUND_UP(mem->memory_size >> PAGE_SHIFT, BITS_PER_LONG) + * sizeof(long)))) + return -EINVAL; slots = __kvm_memslots(kvm, as_id); @@ -2053,7 +2059,8 @@ int __kvm_set_memory_region(struct kvm *kvm, goto out; } if (mem->flags & KVM_MEM_USERFAULT) - new->userfault_bitmap = (unsigned long *)mem->userfault_bitmap; + new->userfault_bitmap = + (unsigned long __user *)(unsigned long)mem->userfault_bitmap; r = kvm_set_memslot(kvm, old, new, change); if (r)