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Re: [Xen-devel] [RFC v3 3/6] xen/arm: Add save/restore support for ARM arch timer

On 05/14/2014 06:14 AM, Ian Campbell wrote:
On Thu, 2014-05-08 at 16:18 -0500, Wei Huang wrote:
This patch implements a save/resore support for ARM architecture


diff --git a/xen/include/public/arch-arm/hvm/save.h 
index 421a6f6..8679bfd 100644
--- a/xen/include/public/arch-arm/hvm/save.h
+++ b/xen/include/public/arch-arm/hvm/save.h
@@ -72,10 +72,24 @@ struct hvm_arm_gich_v2
  DECLARE_HVM_SAVE_TYPE(GICH_V2, 3, struct hvm_arm_gich_v2);

+/* Two ARM timers (physical and virtual) are saved */

Do you not need to save CNTFRQ and CNTKCTL?

+#define ARM_TIMER_TYPE_COUNT 2       /* total count */
+struct hvm_arm_timer
+    uint64_t vtb_offset;

As discussed elsewhere I don't think the offset is architectural state.
This should be incorporated into the cval. Otherwise how does the
receiver know what this is an offset from?

+    uint32_t ctl;
+    uint64_t cval;
+    uint32_t type;
+DECLARE_HVM_SAVE_TYPE(TIMER, 4, struct hvm_arm_timer);

Why not do
DECLARE_HVM_SAVE_TYPE(VTIMER, 4, struct hvm_arm_timer)
DECLARE_HVM_SAVE_TYPE(PTIMER, 5, struct hvm_arm_timer)
and drop the type field?

Or else define hvm_arm_timers with cntfeq, cntkctl and two sets of the
ctl,cval in a single struct.

This is the preferred approach after discussing with Julien.

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