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Re: [Xen-devel] [PATCH v2 07/14] svm: Remove redundant TSC scaling in svm_set_tsc_offset()
On 12/06/2015 03:58 PM, Haozhong Zhang wrote:
Now every caller passes an already scaled offset to
svm_set_tsc_offset(), so it's not necessary to recalculate a scaled TSC
offset in svm_set_tsc_offset().
Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
xen/arch/x86/hvm/svm/svm.c | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 9d5f2c3..3d22dfa 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -826,19 +826,7 @@ static void svm_set_tsc_offset(struct vcpu *v, u64 offset,
u64 at_tsc)
struct vmcb_struct *n1vmcb, *n2vmcb;
uint64_t n2_tsc_offset = 0;
struct domain *d = v->domain;
- uint64_t host_tsc, guest_tsc;
-
- guest_tsc = hvm_get_guest_tsc_fixed(v, at_tsc);
-
- /* Re-adjust the offset value when TSC_RATIO is available */
- if ( cpu_has_tsc_ratio && !d->arch.vtsc )
- {
- if ( at_tsc )
- host_tsc = at_tsc;
- else
- host_tsc = rdtsc();
- offset = svm_get_tsc_offset(host_tsc, guest_tsc, vcpu_tsc_ratio(v));
- }
+ uint64_t guest_tsc;
You could declare it at the first use site below.
Other than that,
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
if ( !nestedhvm_enabled(d) ) {
vmcb_set_tsc_offset(vmcb, offset);
@@ -854,6 +842,7 @@ static void svm_set_tsc_offset(struct vcpu *v, u64 offset,
u64 at_tsc)
n2_tsc_offset = vmcb_get_tsc_offset(n2vmcb) -
vmcb_get_tsc_offset(n1vmcb);
if ( svm->ns_tscratio != DEFAULT_TSC_RATIO ) {
+ guest_tsc = hvm_get_guest_tsc_fixed(v, at_tsc);
n2_tsc_offset = svm_get_tsc_offset(guest_tsc,
guest_tsc + n2_tsc_offset, svm->ns_tscratio);
}
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