Commit f7c90c2a authored by Juergen Gross's avatar Juergen Gross Committed by Boris Ostrovsky

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

Change the code to use hypercalls instead.
Signed-off-by: default avatarJuergen Gross <>
Reviewed-by: default avatarJan Beulich <>
Signed-off-by: default avatarBoris Ostrovsky <>
parent 75f2d3a0
......@@ -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) &
native_set_pte(ptep, pte);
__xen_set_pte(ptep, pte);
/* Early in boot, while setting up the initial pagetable, assume
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