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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Xiaoyao Li" <xiaoyao.li@intel.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Jim Mattson" <jmattson@google.com>
Subject: Re: [PATCH] KVM: X86: Make fpu allocation a common function
Date: Tue, 15 Oct 2019 12:53:20 +0200	[thread overview]
Message-ID: <87v9sq46vz.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20191014183723.GE22962@linux.intel.com>

Sean Christopherson <sean.j.christopherson@intel.com> writes:

> On Mon, Oct 14, 2019 at 06:58:49PM +0200, Vitaly Kuznetsov wrote:
>> Xiaoyao Li <xiaoyao.li@intel.com> writes:
>> 
>> > They are duplicated codes to create vcpu.arch.{user,guest}_fpu in VMX
>> > and SVM. Make them common functions.
>> >
>> > No functional change intended.
>> 
>> Would it rather make sense to move this code to
>> kvm_arch_vcpu_create()/kvm_arch_vcpu_destroy() instead?
>
> Does it make sense?  Yes.  Would it actually work?  No.  Well, not without
> other shenanigans.
>
> FPU allocation can't be placed after the call to .create_vcpu() becuase
> it's consumed in kvm_arch_vcpu_init().   FPU allocation can't come before
> .create_vcpu() because the vCPU struct itself hasn't been allocated.

A very theoretical question: why do we have 'struct vcpu' embedded in
vcpu_vmx/vcpu_svm and not the other way around (e.g. in a union)? That
would've allowed us to allocate memory in common code and then fill in
vendor-specific details in .create_vcpu().

-- 
Vitaly

  parent reply	other threads:[~2019-10-15 10:53 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-14 16:22 [PATCH] KVM: X86: Make fpu allocation a common function Xiaoyao Li
2019-10-14 16:58 ` Vitaly Kuznetsov
2019-10-14 18:37   ` Sean Christopherson
2019-10-15  0:48     ` Xiaoyao Li
2019-10-15 10:53     ` Vitaly Kuznetsov [this message]
2019-10-15 14:27       ` Paolo Bonzini
2019-10-15 14:36         ` Vitaly Kuznetsov
2019-10-15 16:14           ` Sean Christopherson
2019-10-15 16:36           ` Paolo Bonzini
2019-10-15  9:28   ` Paolo Bonzini
2019-10-16  1:52     ` Xiaoyao Li
2019-10-16  7:35       ` Paolo Bonzini
2019-10-16  7:48         ` Xiaoyao Li
2019-10-16  9:41           ` Paolo Bonzini
2019-10-17 16:05             ` Sean Christopherson
2019-10-21 13:09               ` Paolo Bonzini
2019-10-22  0:57                 ` Xiaoyao Li

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