linux-kernel - Re: [RFC PATCH] kvm: x86/vmx: Use kzalloc for cached

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Date:   Thu, 24 Jan 2019 02:18:26 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Tom Roeder <tmroeder@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Liran Alon <liran.alon@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot+ded1696f6b50b615b630@...kaller.appspotmail.com
Subject: Re: [RFC PATCH] kvm: x86/vmx: Use kzalloc for cached_vmcs12

On 23/01/19 19:33, Tom Roeder wrote:
> 
> Even in vmx_set_nested_state, there are about 30 lines of code in
> between enter_vmx_operation and copy_from_user, and there are a couple
> of cases that cause vmx_set_nested_state to return with an error. So if
> we want to fix this by handling all the error paths, I think it might be
> cleanest to convert vmx_set_nested_state to use goto error handling,
> since that would allow us to clear the allocated memory in one place.

I prefer to have kzalloc, and change vmx_get_nested_state to copy the
whole page including the trailing zeroes.

Paolo