[Xen-devel] [PATCH v2 3/3] xen: prevent access to HPET from Dom0

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Prevent Dom0 from accessing HPET MMIO region by adding the HPET mfn to the
list of read-only memory regions.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes since v1:
 - Instead of completely blocking access to the HPET mfn, set it as
   read-only.
---
 xen/arch/x86/domain_build.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index 41d2541..4c62bb8 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -36,6 +36,7 @@
 #include <asm/bzimage.h> /* for bzimage_parse */
 #include <asm/io_apic.h>
 #include <asm/hap.h>
+#include <asm/hpet.h> /* for hpet_address */
 
 #include <public/version.h>
 
@@ -1494,6 +1495,13 @@ int __init construct_dom0(
             rc |= iomem_deny_access(d, sfn, efn);
     }
 
+    /* Prevent access to HPET */
+    if ( hpet_address != 0 )
+    {
+        mfn = paddr_to_pfn(hpet_address);
+        rc |= rangeset_add_singleton(mmio_ro_ranges, mfn);
+    }
+
     BUG_ON(rc != 0);
 
     if ( elf_check_broken(&elf) )
-- 
1.9.3 (Apple Git-50)


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