linux-kernel - Re: [PATCH v14 072/113] KVM: TDX: handle vcpu migration over logical processor

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Date:   Mon, 17 Jul 2023 10:12:38 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     "Wen, Qian" <qian.wen@...el.com>
Cc:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
        Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Kai Huang <kai.huang@...el.com>,
        Zhi Wang <zhi.wang.linux@...il.com>, chen.bo@...el.com
Subject: Re: [PATCH v14 072/113] KVM: TDX: handle vcpu migration over logical
 processor

On Wed, Jul 12, 2023 at 02:08:15PM +0800,
"Wen, Qian" <qian.wen@...el.com> wrote:

> On 5/29/2023 12:19 PM, isaku.yamahata@...el.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@...el.com>
> > 
> > For vcpu migration, in the case of VMX, VMCS is flushed on the source pcpu,
> > and load it on the target pcpu.  There are corresponding TDX SEAMCALL APIs,
> > call them on vcpu migration.  The logic is mostly same as VMX except the
> > TDX SEAMCALLs are used.
> > 
> > When shutting down the machine, (VMX or TDX) vcpus needs to be shutdown on
> > each pcpu.  Do the similar for TDX with TDX SEAMCALL APIs.
> > 
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> > ---
> >  arch/x86/kvm/vmx/main.c    |  32 ++++++-
> >  arch/x86/kvm/vmx/tdx.c     | 168 +++++++++++++++++++++++++++++++++++++
> >  arch/x86/kvm/vmx/tdx.h     |   2 +
> >  arch/x86/kvm/vmx/x86_ops.h |   4 +
> >  4 files changed, 203 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> > index 17fb1515e56a..29ebd171dbe3 100644
> 
> ...
> 
> > @@ -455,6 +606,19 @@ void tdx_vcpu_free(struct kvm_vcpu *vcpu)
> >  		return;
> >  	}
> >  
> > +	/*
> > +	 * kvm_free_vcpus()
> > +	 *   -> kvm_unload_vcpu_mmu()
> > +	 *
> > +	 * does vcpu_load() for every vcpu after they already disassociated
> > +	 * from the per cpu list when tdx_vm_teardown(). So we need to
> > +	 * disassociate them again, otherwise the freed vcpu data will be
> > +	 * accessed when do list_{del,add}() on associated_tdvcpus list
> > +	 * later.
> > +	 */
> 
> Nit: kvm_free_vcpus() and tdx_vm_teardown() are typos? I don't find these functions.

kvm_free_vcpus() => kvm_destroy_vcpus()
tdx_vm_teardown() => tdx_mmu_release_hkid()

Will fix the comment.
-- 
Isaku Yamahata <isaku.yamahata@...il.com>