Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>
Cc:     David Rientjes <rientjes@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        Will Drewry <wad@chromium.org>,
        "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
        "Kleen, Andi" <andi.kleen@intel.com>, x86@kernel.org,
        kvm@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [RFC 08/16] KVM: x86: Use GUP for page walk instead of __get_user()
Date:   Fri, 22 May 2020 15:52:06 +0300
Message-Id: <20200522125214.31348-9-kirill.shutemov@linux.intel.com>
In-Reply-To: <20200522125214.31348-1-kirill.shutemov@linux.intel.com>
References: <20200522125214.31348-1-kirill.shutemov@linux.intel.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The user mapping doesn't have the page mapping for protected memory.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/x86/kvm/mmu/paging_tmpl.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 9bdf9b7d9a96..ef0c5bc8ad7e 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -400,8 +400,14 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 			goto error;
 
 		ptep_user = (pt_element_t __user *)((void *)host_addr + offset);
-		if (unlikely(__get_user(pte, ptep_user)))
-			goto error;
+		if (vcpu->kvm->mem_protected) {
+			if (copy_from_guest(&pte, host_addr + offset,
+					    sizeof(pte)))
+				goto error;
+		} else {
+			if (unlikely(__get_user(pte, ptep_user)))
+				goto error;
+		}
 		walker->ptep_user[walker->level - 1] = ptep_user;
 
 		trace_kvm_mmu_paging_element(pte, walker->level);
-- 
2.26.2