[Xen-devel] [PATCH 6/6] x86/vvmx: Fix auditing of MSR_BITMAP parameter

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The MSR_BITMAP field is required to be page aligned.  Also switch gpa to be a
uint64_t, as the MSR_BITMAP is strictly a 64bit VMCS field.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vvmx.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index f84478e..6ee5385 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -754,14 +754,27 @@ static void __clear_current_vvmcs(struct vcpu *v)
         __vmpclear(nvcpu->nv_n2vmcx_pa);
 }
 
-static bool_t __must_check _map_msr_bitmap(struct vcpu *v)
+/*
+ * Refreshes the MSR bitmap mapping for the current nested vcpu.  Returns true
+ * for a success mapping, and returns false for MSR_BITMAP parameter errors or
+ * gfn mapping errors.
+ */
+static bool __must_check _map_msr_bitmap(struct vcpu *v)
 {
     struct nestedvmx *nvmx = &vcpu_2_nvmx(v);
-    unsigned long gpa;
+    uint64_t gpa;
 
     if ( nvmx->msrbitmap )
+    {
         hvm_unmap_guest_frame(nvmx->msrbitmap, 1);
+        nvmx->msrbitmap = NULL;
+    }
+
     gpa = get_vvmcs(v, MSR_BITMAP);
+
+    if ( !IS_ALIGNED(gpa, PAGE_SIZE) )
+        return false;
+
     nvmx->msrbitmap = hvm_map_guest_frame_ro(gpa >> PAGE_SHIFT, 1);
 
     return nvmx->msrbitmap != NULL;
-- 
2.1.4


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