From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
Tom Roeder <tmroeder@google.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>,
"Liran Alon" <liran.alon@oracle.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org,
syzbot+ded1696f6b50b615b630@syzkaller.appspotmail.com
Subject: Re: [RFC PATCH] kvm: x86/vmx: Use kzalloc for cached_vmcs12
Date: Tue, 15 Jan 2019 11:15:51 +0100 [thread overview]
Message-ID: <2177074d-f610-0d86-7399-e63ba851346c@redhat.com> (raw)
In-Reply-To: <20190115024304.GD5141@linux.intel.com>
On 15/01/19 03:43, Sean Christopherson wrote:
>> - vmx->nested.cached_vmcs12 = kmalloc(VMCS12_SIZE, GFP_KERNEL);
>> + vmx->nested.cached_vmcs12 = kzalloc(VMCS12_SIZE, GFP_KERNEL);
>> if (!vmx->nested.cached_vmcs12)
>> goto out_cached_vmcs12;
> Obviously not your code, but why do we allocate VMCS12_SIZE instead of
> sizeof(struct vmcs12)? I get why we require userspace to reserve the
> full 4k, but I don't understand why KVM needs to allocate the reserved
> bytes internally.
It's just cleaner and shorter code to copy everything in and out,
instead of having to explicitly zero the slack.
Paolo
next prev parent reply other threads:[~2019-01-15 10:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-07 1:38 KMSAN: kernel-infoleak in kvm_vcpu_write_guest_page syzbot
2018-11-07 12:10 ` Alexander Potapenko
2018-11-07 12:47 ` Paolo Bonzini
2018-11-07 12:58 ` Liran Alon
2018-11-07 13:37 ` Paolo Bonzini
2019-01-14 23:47 ` [RFC PATCH] kvm: x86/vmx: Use kzalloc for cached_vmcs12 Tom Roeder
2019-01-15 0:03 ` Jim Mattson
2019-01-15 2:43 ` Sean Christopherson
2019-01-15 10:15 ` Paolo Bonzini [this message]
2019-01-23 18:25 ` Tom Roeder
2019-01-24 1:17 ` Paolo Bonzini
2019-01-15 17:51 ` Tom Roeder
2019-01-23 18:33 ` Tom Roeder
2019-01-24 1:18 ` Paolo Bonzini
2019-01-24 21:46 ` Tom Roeder
2018-11-07 12:52 ` KMSAN: kernel-infoleak in kvm_vcpu_write_guest_page Liran Alon
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