[Xen-devel] [PATCH 1/1] x86/AMD: Fix nested svm crash due to assertion in __virt_to_maddr

[<suravee.suthikulpanit@xxxxxxx>]

From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>

Fix assertion in __virt_to_maddr when starting nested SVM guest
in debug mode. Investigation has shown that svm_vmsave/svm_vmload
make use of __pa() with invalid address.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
 xen/arch/x86/hvm/svm/svm.c        |    4 ++--
 xen/include/asm-x86/hvm/svm/svm.h |   14 ++++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index acd2d49..944569a 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1809,7 +1809,7 @@ svm_vmexit_do_vmload(struct vmcb_struct *vmcb,
         goto inject;
     }
 
-    svm_vmload(nv->nv_vvmcx);
+    nestedsvm_vmload(nv->nv_vvmcxaddr);
     /* State in L1 VMCB is stale now */
     v->arch.hvm_svm.vmcb_in_sync = 0;
 
@@ -1845,7 +1845,7 @@ svm_vmexit_do_vmsave(struct vmcb_struct *vmcb,
         goto inject;
     }
 
-    svm_vmsave(nv->nv_vvmcx);
+    nestedsvm_vmsave(nv->nv_vvmcxaddr);
 
     __update_guest_eip(regs, inst_len);
     return;
diff --git a/xen/include/asm-x86/hvm/svm/svm.h 
b/xen/include/asm-x86/hvm/svm/svm.h
index 64e7e25..909e8a1 100644
--- a/xen/include/asm-x86/hvm/svm/svm.h
+++ b/xen/include/asm-x86/hvm/svm/svm.h
@@ -55,6 +55,20 @@ static inline void svm_vmsave(void *vmcb)
         : : "a" (__pa(vmcb)) : "memory" );
 }
 
+static inline void nestedsvm_vmload(uint64_t vmcb)
+{
+    asm volatile (
+        ".byte 0x0f,0x01,0xda" /* vmload */
+        : : "a" (vmcb) : "memory" );
+}
+
+static inline void nestedsvm_vmsave(uint64_t vmcb)
+{
+    asm volatile (
+        ".byte 0x0f,0x01,0xdb" /* vmsave */
+        : : "a" (vmcb) : "memory" );
+}
+
 static inline void svm_invlpga(unsigned long vaddr, uint32_t asid)
 {
     asm volatile (
-- 
1.7.10.4



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