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Shutemov" To: "Edgecombe, Rick P" Cc: "peterz@infradead.org" , "jmattson@google.com" , "Christopherson, Sean J" , "vkuznets@redhat.com" , "dave.hansen@linux.intel.com" , "joro@8bytes.org" , "luto@kernel.org" , "pbonzini@redhat.com" , "wanpengli@tencent.com" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "kirill.shutemov@linux.intel.com" , "keescook@chromium.org" , "rppt@kernel.org" , "linux-mm@kvack.org" , "x86@kernel.org" , "aarcange@redhat.com" , "liran.alon@oracle.com" , "wad@chromium.org" , "rientjes@google.com" , "Kleen, Andi" Subject: Re: [RFCv2 14/16] KVM: Handle protected memory in __kvm_map_gfn()/__kvm_unmap_gfn() Message-ID: <20201022120645.vdmytvcmdoku73os@box> References: <20201020061859.18385-1-kirill.shutemov@linux.intel.com> <20201020061859.18385-15-kirill.shutemov@linux.intel.com> <8404a8802dbdbf81c8f75249039580f9e6942095.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8404a8802dbdbf81c8f75249039580f9e6942095.camel@intel.com> 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: On Wed, Oct 21, 2020 at 06:50:28PM +0000, Edgecombe, Rick P wrote: > On Tue, 2020-10-20 at 09:18 +0300, Kirill A. Shutemov wrote: > > @@ -467,7 +477,7 @@ void iounmap(volatile void __iomem *addr) > > p = find_vm_area((void __force *)addr); > > > > if (!p) { > > - printk(KERN_ERR "iounmap: bad address %p\n", addr); > > + printk(KERN_ERR "iounmap: bad address %px\n", addr); > > Unintentional? Yep. Will fix. > > @@ -2162,15 +2178,20 @@ static int __kvm_map_gfn(struct kvm_memslots > > *slots, gfn_t gfn, > > kvm_cache_gfn_to_pfn(slot, gfn, cache, gen); > > } > > pfn = cache->pfn; > > + protected = cache->protected; > > } else { > > if (atomic) > > return -EAGAIN; > > - pfn = gfn_to_pfn_memslot(slot, gfn); > > + pfn = gfn_to_pfn_memslot_protected(slot, gfn, > > &protected); > > } > > if (is_error_noslot_pfn(pfn)) > > return -EINVAL; > > > > - if (pfn_valid(pfn)) { > > + if (protected) { > > + if (atomic) > > + return -EAGAIN; > > + hva = ioremap_cache_force(pfn_to_hpa(pfn), PAGE_SIZE); > > + } else if (pfn_valid(pfn)) { > > page = pfn_to_page(pfn); > > if (atomic) > > hva = kmap_atomic(page); > > I think the page could have got unmapped since the gup via the > hypercall on another CPU. It could be an avenue for the guest to crash > the host. Hm.. I'm not sure I follow. Could you elaborate on what scenario you have in mind? -- Kirill A. Shutemov