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From: Michael Roth <michael.roth@amd.com>
To: kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Subject: [PATCH 0/3] KVM: SVM: Refactor vcpu_load/put to use vmload/vmsave for host state
Date: Tue,  5 Jan 2021 08:37:47 -0600	[thread overview]
Message-ID: <20210105143749.557054-1-michael.roth@amd.com> (raw)

This series re-works the SVM KVM implementation to use vmload/vmsave to
handle saving/restoring additional host MSRs rather than explicit MSR
read/writes, resulting in a significant performance improvement for some
specific workloads and simplifying some of the save/load code (PATCH 1).

With those changes some commonalities emerge between SEV-ES and normal
vcpu_load/vcpu_put paths, which we then take advantage of to share more code,
as well as refactor them in a way that more closely aligns with the VMX
implementation (PATCH 2 and 3).

 - rebased on kvm-next
 - remove uneeded braces from host MSR save/load loops (Sean)
 - use page_to_phys() in place of page_to_pfn() and shifting (Sean)
 - use stack instead of struct field to cache host save area outside of
   per-cpu storage, and pass as an argument to __svm_vcpu_run() to
   handle the VMLOAD in ASM code rather than inlining ASM (Sean/Andy)
 - remove now-uneeded index/sev_es_restored fields from
   host_save_user_msrs list
 - move host-saving/guest-loading of registers to prepare_guest_switch(),
   and host-loading of registers to prepare_host_switch, for both normal
   and sev-es paths (Sean)

 - rebase on latest kvm/next
 - move VMLOAD to just after vmexit so we can use it to handle all FS/GS
   host state restoration and rather than relying on loadsegment() and
   explicit write to MSR_GS_BASE (Andy)
 - drop 'host' field from struct vcpu_svm since it is no longer needed
   for storing FS/GS/LDT state (Andy)

 arch/x86/kvm/svm/sev.c     |  30 +-----------------------------
 arch/x86/kvm/svm/svm.c     | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------------------------------------------
 arch/x86/kvm/svm/svm.h     |  31 ++++++-------------------------
 arch/x86/kvm/svm/vmenter.S |  10 ++++++++++
 4 files changed, 75 insertions(+), 108 deletions(-)

             reply	other threads:[~2021-01-05 14:39 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-05 14:37 Michael Roth [this message]
2021-01-05 14:37 ` [PATCH v3 1/3] KVM: SVM: use vmsave/vmload for saving/restoring additional host state Michael Roth
2021-01-05 17:20   ` Sean Christopherson
2021-01-07 15:32     ` Tom Lendacky
2021-01-07 15:47       ` Tom Lendacky
2021-01-08  0:32     ` Michael Roth
2021-02-02 17:32     ` Paolo Bonzini
2021-01-07 15:39   ` Tom Lendacky
2021-01-05 14:37 ` [PATCH v3 2/3] KVM: SVM: remove uneeded fields from host_save_users_msrs Michael Roth
2021-01-05 14:37 ` [PATCH v3 3/3] KVM: SVM: use .prepare_guest_switch() to handle CPU register save/setup Michael Roth

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