From: Paolo Bonzini <pbonzini@redhat.com>
To: Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org
Cc: 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>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 0/3] KVM: SVM: Refactor vcpu_load/put to use vmload/vmsave for host state
Date: Wed, 3 Feb 2021 09:10:49 +0100 [thread overview]
Message-ID: <bad29417-94de-bbf6-a2ea-765bfc78f25b@redhat.com> (raw)
In-Reply-To: <20210202190126.2185715-1-michael.roth@amd.com>
On 02/02/21 20:01, Michael Roth wrote:
> Hi Sean, Paolo,
>
> Following up from previous v3 discussion:
>
> https://lore.kernel.org/kvm/X%2FSfw15OWarseivB@google.com/
>
> I got bit in internal testing by a bug in v3 of this series that Sean had
> already pointed out in v3 comments, so I thought it might be good to go
> ahead and send a v4 with those fixes included. I also saw that Sean's vmsave
> helpers are now in kvm/queue, so I've rebased these on top of those, and
> made use of the new vmsave/vmload helpers:
>
> https://lore.kernel.org/kvm/8880fedc-14aa-1f14-b87b-118ebe0932a2@redhat.com/
>
> Thanks!
>
> -Mike
>
> = Overview =
>
> 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).
Queued, thanks.
Paolo
> v4:
> - rebased on kvm/queue
> - use sme_page_pa() when accessing save area (Sean)
> - make sure vmload during host reboot is handled (Sean)
> - introduce vmload() helper like we have with vmsave(), use that instead
> of moving the introduce to ASM (Sean)
>
> v3:
> - 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)
>
> v2:
> - 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 | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------------------------------------
> arch/x86/kvm/svm/svm.h | 29 +++++------------------------
> arch/x86/kvm/svm/svm_ops.h | 5 +++++
> 4 files changed, 67 insertions(+), 104 deletions(-)
>
>
prev parent reply other threads:[~2021-02-03 8:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 19:01 [PATCH v4 0/3] KVM: SVM: Refactor vcpu_load/put to use vmload/vmsave for host state Michael Roth
2021-02-02 19:01 ` [PATCH v4 1/3] KVM: SVM: use vmsave/vmload for saving/restoring additional " Michael Roth
2021-02-03 0:38 ` Sean Christopherson
2021-02-03 8:04 ` Paolo Bonzini
2021-02-02 19:01 ` [PATCH v4 2/3] KVM: SVM: remove uneeded fields from host_save_users_msrs Michael Roth
2021-02-02 19:01 ` [PATCH v4 3/3] KVM: SVM: use .prepare_guest_switch() to handle CPU register save/setup Michael Roth
2021-02-03 8:10 ` Paolo Bonzini [this message]
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