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Date: Tue, 21 Aug 2018 17:37:54 +0200 From: Juergen Gross <jgross@...e.com> To: linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org, x86@...nel.org Cc: boris.ostrovsky@...cle.com, hpa@...or.com, tglx@...utronix.de, mingo@...hat.com, Juergen Gross <jgross@...e.com> Subject: [PATCH v2 1/2] x86/xen: don't write ptes directly in 32-bit PV guests 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 <jgross@...e.com> Reviewed-by: Jan Beulich <jbeulich@...e.com> --- arch/x86/xen/mmu_pv.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index 9e7012858420..9396b4d17064 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -434,14 +434,13 @@ static void xen_set_pud(pud_t *ptr, pud_t val) 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) @@ -1569,7 +1568,7 @@ static void __init xen_set_pte_init(pte_t *ptep, pte_t 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 -- 2.13.7
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