Re: [Xen-devel] [PATCH] svm: Do not intercept RDTCS(P) when TSC scaling is supported by hardware

["Huang2, Wei" <Wei.Huang2@xxxxxxx>]

Please also backport this patch to xen-4.1. Thanks.

-Wei

-----Original Message-----
From: Boris Ostrovsky [mailto:boris.ostrovsky@xxxxxxx] 
Sent: Thursday, April 19, 2012 9:21 PM
To: JBeulich@xxxxxxxx; keir@xxxxxxx
Cc: Ostrovsky, Boris; Huang2, Wei; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [PATCH] svm: Do not intercept RDTCS(P) when TSC scaling is supported 
by hardware

# HG changeset patch
# User Boris Ostrovsky <boris.ostrovsky@xxxxxxx>
# Date 1334875170 14400
# Node ID 55bf11ebce87ceb73fb2c372dcef170ec0bb4a18
# Parent  7c777cb8f705411b77c551f34ba88bdc09e38ab8
svm: Do not intercept RDTCS(P) when TSC scaling is supported by hardware

When running in TSC_MODE_ALWAYS_EMULATE mode on processors that support
TSC scaling we don't need to intercept RDTSC/RDTSCP instructions.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxx>
Acked-by: Wei Huang <wei.huang2@xxxxxxx>
Tested-by: Wei Huang <wei.huang2@xxxxxxx>

diff -r 7c777cb8f705 -r 55bf11ebce87 xen/arch/x86/hvm/svm/svm.c
--- a/xen/arch/x86/hvm/svm/svm.c        Wed Apr 18 16:49:55 2012 +0100
+++ b/xen/arch/x86/hvm/svm/svm.c        Thu Apr 19 18:39:30 2012 -0400
@@ -724,12 +724,18 @@ static void svm_set_rdtsc_exiting(struct
 {
     struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
     u32 general1_intercepts = vmcb_get_general1_intercepts(vmcb);
+    u32 general2_intercepts = vmcb_get_general2_intercepts(vmcb);
 
     general1_intercepts &= ~GENERAL1_INTERCEPT_RDTSC;
-    if ( enable )
+    general2_intercepts &= ~GENERAL2_INTERCEPT_RDTSCP;
+
+    if ( enable && !cpu_has_tsc_ratio ) {
         general1_intercepts |= GENERAL1_INTERCEPT_RDTSC;
+        general2_intercepts |= GENERAL2_INTERCEPT_RDTSCP;
+    }
 
     vmcb_set_general1_intercepts(vmcb, general1_intercepts);
+    vmcb_set_general2_intercepts(vmcb, general2_intercepts);
 }
 
 static unsigned int svm_get_insn_bytes(struct vcpu *v, uint8_t *buf)


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel