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From: Jan Beulich <jbeulich@suse.com>
To: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: [PATCH] SVM: avoid VMSAVE in ctxt-switch-to
Date: Mon, 19 Oct 2020 15:40:39 +0200	[thread overview]
Message-ID: <a01862b8-6e16-5ddc-7f48-2d3bed2f34b6@suse.com> (raw)

Of the state saved by the insn and reloaded by the corresponding VMLOAD
- TR, syscall, and sysenter state are invariant while having Xen's state
  loaded,
- FS, GS, and LDTR are not used by Xen and get suitably set in PV
  context switch code.

Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -984,7 +984,6 @@ static void svm_ctxt_switch_to(struct vc
 
     svm_restore_dr(v);
 
-    svm_vmsave_pa(per_cpu(host_vmcb, cpu));
     vmcb->cleanbits.raw = 0;
     svm_tsc_ratio_load(v);
 


             reply	other threads:[~2020-10-19 13:41 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-19 13:40 Jan Beulich [this message]
2020-10-19 14:10 ` [PATCH] SVM: avoid VMSAVE in ctxt-switch-to Andrew Cooper
2020-10-19 14:21   ` Jan Beulich
2020-10-19 14:30     ` Andrew Cooper
2020-10-19 15:02       ` Jan Beulich
2020-10-19 15:22         ` Andrew Cooper
2020-10-19 15:47           ` Jan Beulich
2020-10-19 15:52             ` Andrew Cooper
2020-10-20  7:00               ` Jan Beulich

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