[Xen-changelog] [xen stable-4.12] x86/vvmx: Fix the use of RDTSCP when it is intercepted at L0

[patchbot@xxxxxxx]

commit 58668f12a6e65cd6a384abad001ff5dae69b161f
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Mon Nov 25 15:50:44 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Nov 25 15:50:44 2019 +0100

    x86/vvmx: Fix the use of RDTSCP when it is intercepted at L0
    
    Linux has started using RDTSCP as of v5.1.  This has highlighted a bug in 
Xen,
    where virtual vmexit simply gives up.
    
      (XEN) d1v1 Unhandled nested vmexit: reason 51
      (XEN) domain_crash called from vvmx.c:2671
      (XEN) Domain 1 (vcpu#1) crashed on cpu#2:
    
    Handle RDTSCP in the virtual vmexit hander in the same was as RDTSC
    intercepts.
    
    Reported-by: Sarah Newman <srn@xxxxxxxxx>
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Tested-by: Chris Brannon <cmb@xxxxxxxxx>
    Reviewed-by: Wei Liu <wl@xxxxxxx>
    master commit: 9257c218e56e9902b78662e5852d69329b9cc204
    master date: 2019-10-23 16:43:48 +0100
---
 xen/arch/x86/hvm/vmx/vvmx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index f03660b51e..02c8c0fd50 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -2487,6 +2487,7 @@ int nvmx_n2_vmexit_handler(struct cpu_user_regs *regs,
             nvcpu->nv_vmexit_pending = 1;
         break;
     case EXIT_REASON_RDTSC:
+    case EXIT_REASON_RDTSCP:
         ctrl = __n2_exec_control(v);
         if ( ctrl & CPU_BASED_RDTSC_EXITING )
             nvcpu->nv_vmexit_pending = 1;
@@ -2497,6 +2498,8 @@ int nvmx_n2_vmexit_handler(struct cpu_user_regs *regs,
              * avoiding changing guest_tsc and messing up timekeeping in L1
              */
             msr_split(regs, hvm_get_guest_tsc(v) + get_vvmcs(v, TSC_OFFSET));
+            if ( exit_reason == EXIT_REASON_RDTSCP )
+                regs->rcx = v->arch.msrs->tsc_aux;
             update_guest_eip();
 
             return 1;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12

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