From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Juergen Gross , Jan Beulich , Boris Ostrovsky Subject: [PATCH 4.14 103/115] x86/xen: dont write ptes directly in 32-bit PV guests Date: Thu, 13 Sep 2018 15:32:03 +0200 Message-Id: <20180913131829.701763608@linuxfoundation.org> In-Reply-To: <20180913131823.327472833@linuxfoundation.org> References: <20180913131823.327472833@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Juergen Gross commit f7c90c2aa4004808dff777ba6ae2c7294dd06851 upstream. In some cases 32-bit PAE PV guests still write PTEs directly instead of using hypercalls. This is especially bad when clearing a PTE as this is done via 32-bit writes which will produce intermediate L1TF attackable PTEs. Change the code to use hypercalls instead. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Signed-off-by: Boris Ostrovsky Signed-off-by: Greg Kroah-Hartman --- arch/x86/xen/mmu_pv.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -425,14 +425,13 @@ static void xen_set_pud(pud_t *ptr, pud_ static void xen_set_pte_atomic(pte_t *ptep, pte_t pte) { trace_xen_mmu_set_pte_atomic(ptep, pte); - set_64bit((u64 *)ptep, native_pte_val(pte)); + __xen_set_pte(ptep, pte); } static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { trace_xen_mmu_pte_clear(mm, addr, ptep); - if (!xen_batched_set_pte(ptep, native_make_pte(0))) - native_pte_clear(mm, addr, ptep); + __xen_set_pte(ptep, native_make_pte(0)); } static void xen_pmd_clear(pmd_t *pmdp) @@ -1543,7 +1542,7 @@ static void __init xen_set_pte_init(pte_ pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) & pte_val_ma(pte)); #endif - native_set_pte(ptep, pte); + __xen_set_pte(ptep, pte); } /* Early in boot, while setting up the initial pagetable, assume