[PATCH v7 10/10] x86/vm_event: Carry Processor Trace buffer offset in vm_event

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

From: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>

Add pt_offset field to x86 regs in vm_event. Initialized to ~0 if PT
is not in use.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Michał Leszczyński <michal.leszczynski@xxxxxxx>
CC: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>

v7:
 * New
---
 xen/arch/x86/vm_event.c       | 3 +++
 xen/include/public/vm_event.h | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
index 848d69c1b0..09dfc0924e 100644
--- a/xen/arch/x86/vm_event.c
+++ b/xen/arch/x86/vm_event.c
@@ -251,6 +251,9 @@ void vm_event_fill_regs(vm_event_request_t *req)
 
     req->data.regs.x86.shadow_gs = ctxt.shadow_gs;
     req->data.regs.x86.dr6 = ctxt.dr6;
+
+    if ( hvm_vmtrace_output_position(curr, &req->data.regs.x86.pt_offset) != 1 
)
+        req->data.regs.x86.pt_offset = ~0;
 #endif
 }
 
diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
index 141ea024a3..57f34bf902 100644
--- a/xen/include/public/vm_event.h
+++ b/xen/include/public/vm_event.h
@@ -223,6 +223,12 @@ struct vm_event_regs_x86 {
      */
     uint64_t npt_base;
 
+    /*
+     * Current offset in the Processor Trace buffer. For Intel Processor Trace
+     * this is MSR_RTIT_OUTPUT_MASK. Set to ~0 if no Processor Trace is active.
+     */
+    uint64_t pt_offset;
+
     uint32_t cs_base;
     uint32_t ss_base;
     uint32_t ds_base;
-- 
2.11.0