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[PATCH 6/6] xen/x86: restrict PV Dom0 identity mapping
- To: Juergen Gross <jgross@xxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 30 Sep 2021 14:37:19 +0200
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, lkml <linux-kernel@xxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Thu, 30 Sep 2021 12:37:30 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
When moving away RAM pages, there having been a mapping of those is not
a proper indication that instead MMIO should be mapped there. At the
point in time this effectively covers the low megabyte only. Mapping of
that is, however, the job of init_mem_mapping(). Comparing the two one
can also spot that we've been wrongly (or at least inconsistently) using
PAGE_KERNEL_IO here.
Simply zap any such mappings instead.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -425,13 +425,13 @@ static unsigned long __init xen_set_iden
}
/*
- * If the PFNs are currently mapped, the VA mapping also needs
- * to be updated to be 1:1.
+ * If the PFNs are currently mapped, their VA mappings need to be
+ * zapped.
*/
for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++)
(void)HYPERVISOR_update_va_mapping(
(unsigned long)__va(pfn << PAGE_SHIFT),
- mfn_pte(pfn, PAGE_KERNEL_IO), 0);
+ native_make_pte(0), 0);
return remap_pfn;
}
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