[Xen-changelog] [xen stable-4.3] nested VMX: don't ignore mapping errors

[patchbot@xxxxxxx]

commit 2fa689a16fc91598fc81468c47557abf597bf256
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Nov 27 10:00:08 2013 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Nov 27 10:00:08 2013 +0100

    nested VMX: don't ignore mapping errors
    
    Rather than ignoring failures to map the virtual VMCS as well as MSR or
    I/O port bitmaps, convert those into failures of the respective
    instructions (avoiding to dereference NULL pointers). Ultimately such
    failures should be handled transparently (by using transient mappings
    when they actually need to be accessed, just like nested SVM does).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Eddie Dong <eddie.dong@xxxxxxxxx>
    master commit: e02b14e531a95399fc9d8647ec3cc6f310a7d455
    master date: 2013-11-18 09:39:01 +0100
---
 xen/arch/x86/hvm/vmx/vvmx.c |   48 ++++++++++++++++++++++++++++--------------
 1 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 041c9f6..5c92ac6 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -746,7 +746,7 @@ static void __clear_current_vvmcs(struct vcpu *v)
         __vmpclear(virt_to_maddr(nvcpu->nv_n2vmcx));
 }
 
-static void __map_msr_bitmap(struct vcpu *v)
+static bool_t __must_check _map_msr_bitmap(struct vcpu *v)
 {
     struct nestedvmx *nvmx = &vcpu_2_nvmx(v);
     unsigned long gpa;
@@ -755,9 +755,11 @@ static void __map_msr_bitmap(struct vcpu *v)
         hvm_unmap_guest_frame(nvmx->msrbitmap, 1);
     gpa = __get_vvmcs(vcpu_nestedhvm(v).nv_vvmcx, MSR_BITMAP);
     nvmx->msrbitmap = hvm_map_guest_frame_ro(gpa >> PAGE_SHIFT, 1);
+
+    return nvmx->msrbitmap != NULL;
 }
 
-static void __map_io_bitmap(struct vcpu *v, u64 vmcs_reg)
+static bool_t __must_check _map_io_bitmap(struct vcpu *v, u64 vmcs_reg)
 {
     struct nestedvmx *nvmx = &vcpu_2_nvmx(v);
     unsigned long gpa;
@@ -768,12 +770,14 @@ static void __map_io_bitmap(struct vcpu *v, u64 vmcs_reg)
         hvm_unmap_guest_frame(nvmx->iobitmap[index], 1);
     gpa = __get_vvmcs(vcpu_nestedhvm(v).nv_vvmcx, vmcs_reg);
     nvmx->iobitmap[index] = hvm_map_guest_frame_ro(gpa >> PAGE_SHIFT, 1);
+
+    return nvmx->iobitmap[index] != NULL;
 }
 
-static inline void map_io_bitmap_all(struct vcpu *v)
+static inline bool_t __must_check map_io_bitmap_all(struct vcpu *v)
 {
-   __map_io_bitmap (v, IO_BITMAP_A);
-   __map_io_bitmap (v, IO_BITMAP_B);
+   return _map_io_bitmap(v, IO_BITMAP_A) &&
+          _map_io_bitmap(v, IO_BITMAP_B);
 }
 
 static void nvmx_purge_vvmcs(struct vcpu *v)
@@ -1609,9 +1613,15 @@ int nvmx_handle_vmptrld(struct cpu_user_regs *regs)
     if ( nvcpu->nv_vvmcxaddr == VMCX_EADDR )
     {
         nvcpu->nv_vvmcx = hvm_map_guest_frame_rw(gpa >> PAGE_SHIFT, 1);
-        nvcpu->nv_vvmcxaddr = gpa;
-        map_io_bitmap_all (v);
-        __map_msr_bitmap(v);
+        if ( nvcpu->nv_vvmcx )
+            nvcpu->nv_vvmcxaddr = gpa;
+        if ( !nvcpu->nv_vvmcx ||
+             !map_io_bitmap_all(v) ||
+             !_map_msr_bitmap(v) )
+        {
+            vmreturn(regs, VMFAIL_VALID);
+            goto out;
+        }
     }
 
     if ( cpu_has_vmx_vmcs_shadowing )
@@ -1723,6 +1733,7 @@ int nvmx_handle_vmwrite(struct cpu_user_regs *regs)
     struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
     unsigned long operand; 
     u64 vmcs_encoding;
+    bool_t okay = 1;
 
     if ( decode_vmx_inst(regs, &decode, &operand, 0)
              != X86EMUL_OKAY )
@@ -1731,16 +1742,21 @@ int nvmx_handle_vmwrite(struct cpu_user_regs *regs)
     vmcs_encoding = reg_read(regs, decode.reg2);
     __set_vvmcs(nvcpu->nv_vvmcx, vmcs_encoding, operand);
 
-    if ( vmcs_encoding == IO_BITMAP_A || vmcs_encoding == IO_BITMAP_A_HIGH )
-        __map_io_bitmap (v, IO_BITMAP_A);
-    else if ( vmcs_encoding == IO_BITMAP_B || 
-              vmcs_encoding == IO_BITMAP_B_HIGH )
-        __map_io_bitmap (v, IO_BITMAP_B);
+    switch ( vmcs_encoding )
+    {
+    case IO_BITMAP_A: case IO_BITMAP_A_HIGH:
+        okay = _map_io_bitmap(v, IO_BITMAP_A);
+        break;
+    case IO_BITMAP_B: case IO_BITMAP_B_HIGH:
+        okay = _map_io_bitmap(v, IO_BITMAP_B);
+        break;
+    case MSR_BITMAP: case MSR_BITMAP_HIGH:
+        okay = _map_msr_bitmap(v);
+        break;
+    }
 
-    if ( vmcs_encoding == MSR_BITMAP || vmcs_encoding == MSR_BITMAP_HIGH )
-        __map_msr_bitmap(v);
+    vmreturn(regs, okay ? VMSUCCEED : VMFAIL_VALID);
 
-    vmreturn(regs, VMSUCCEED);
     return X86EMUL_OKAY;
 }
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.3

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