[Xen-changelog] [xen stable-4.2] x86/vtsc: update vcpu_time in hvm_set_guest_time

[patchbot@xxxxxxx]

commit 3990446a39c17222729437e606f8d10641e3bdda
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Thu Jun 13 11:26:53 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Jun 13 11:26:53 2013 +0200

    x86/vtsc: update vcpu_time in hvm_set_guest_time
    
    When using a vtsc, hvm_set_guest_time changes hvm_vcpu.stime_offset,
    which is used in the vcpu time structure to calculate the
    tsc_timestamp, so after updating stime_offset we need to propagate the
    change to vcpu_time in order for the guest to get the right time if
    using the PV clock.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
    master commit: 32c864a35ece2c24a336d183869a546798a4b241
    master date: 2013-06-05 10:03:08 +0200
---
 xen/arch/x86/hvm/vpt.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/hvm/vpt.c b/xen/arch/x86/hvm/vpt.c
index 353eda0..ec0aba6 100644
--- a/xen/arch/x86/hvm/vpt.c
+++ b/xen/arch/x86/hvm/vpt.c
@@ -56,7 +56,19 @@ u64 hvm_get_guest_time(struct vcpu *v)
 
 void hvm_set_guest_time(struct vcpu *v, u64 guest_time)
 {
-    v->arch.hvm_vcpu.stime_offset += guest_time - hvm_get_guest_time(v);
+    u64 offset = guest_time - hvm_get_guest_time(v);
+
+    if ( offset )
+    {
+        v->arch.hvm_vcpu.stime_offset += offset;
+        /*
+         * If hvm_vcpu.stime_offset is updated make sure to
+         * also update vcpu time, since this value is used to
+         * calculate the TSC.
+         */
+        if ( v == current )
+            update_vcpu_system_time(v);
+    }
 }
 
 static int pt_irq_vector(struct periodic_time *pt, enum hvm_intsrc src)
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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