4.18-stable review patch. If anyone has any objections, please let me know.
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From: Juergen Gross jgross@suse.com
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 jgross@suse.com Reviewed-by: Jan Beulich jbeulich@suse.com Signed-off-by: Boris Ostrovsky boris.ostrovsky@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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 @@ -434,14 +434,13 @@ 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) @@ -1571,7 +1570,7 @@ 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