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Commit 9ef621d3 authored by Tan, Li's avatar Tan, Li Committed by Avi Kivity
Browse files

KVM: Support mixed endian machines 



Currently kvmtrace is not portable. This will prevent from copying a
trace file from big-endian target to little-endian workstation for analysis.
In the patch, kernel outputs metadata containing a magic number to trace
log, and changes 64-bit words to be u64 instead of a pair of u32s.

Signed-off-by: default avatarTan Li <li.tan@intel.com>
Acked-by: default avatarJerone Young <jyoung5@us.ibm.com>
Acked-by: default avatarHollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 25be4608

include/linux/kvm.h

+2 −2
Original line number Diff line number Diff line
@@ -318,14 +318,14 @@ struct kvm_trace_rec { 
	__u32 vcpu_id;

	union {

		struct {

			__u32 cycle_lo, cycle_hi;

			__u64 cycle_u64;

			__u32 extra_u32[KVM_TRC_EXTRA_MAX];

		} cycle;

		struct {

			__u32 extra_u32[KVM_TRC_EXTRA_MAX];

		} nocycle;

	} u;

};

} __attribute__((packed));



#define KVMIO 0xAE

virt/kvm/kvm_trace.c

+12 −6
Original line number Diff line number Diff line
@@ -72,11 +72,7 @@ static void kvm_add_trace(void *probe_private, void *call_data, 
	rec.cycle_in 	= p->cycle_in;



	if (rec.cycle_in) {

		u64 cycle = 0;



		cycle = get_cycles();

		rec.u.cycle.cycle_lo = (u32)cycle;

		rec.u.cycle.cycle_hi = (u32)(cycle >> 32);

		rec.u.cycle.cycle_u64 = get_cycles();



		for (i = 0; i < rec.extra_u32; i++)

			rec.u.cycle.extra_u32[i] = va_arg(*args, u32);
@@ -114,8 +110,18 @@ static int kvm_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, 
{

	struct kvm_trace *kt;



	if (!relay_buf_full(buf))

	if (!relay_buf_full(buf)) {

		if (!prev_subbuf) {

			/*

			 * executed only once when the channel is opened

			 * save metadata as first record

			 */

			subbuf_start_reserve(buf, sizeof(u32));

			*(u32 *)subbuf = 0x12345678;

		}



		return 1;

	}



	kt = buf->chan->private_data;

	atomic_inc(&kt->lost_records);