linux-kernel - Re: [PATCH -next] KVM: SVM: Remove unnecessary GFP_KERNEL_ACCOUNT in svm_set_nested

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b3c27ca7-a409-4df5-bb55-3c3314347d7d@intel.com>
Date: Fri, 23 Aug 2024 12:03:28 +1200
From: "Huang, Kai" <kai.huang@...el.com>
To: Yongqiang Liu <liuyongqiang13@...wei.com>, <kvm@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <zhangxiaoxu5@...wei.com>,
	<hpa@...or.com>, <x86@...nel.org>, <dave.hansen@...ux.intel.com>,
	<bp@...en8.de>, <mingo@...hat.com>, <tglx@...utronix.de>,
	<pbonzini@...hat.com>, <seanjc@...gle.com>
Subject: Re: [PATCH -next] KVM: SVM: Remove unnecessary GFP_KERNEL_ACCOUNT in
 svm_set_nested_state()



On 21/08/2024 11:27 pm, Yongqiang Liu wrote:
> The fixed size temporary variables vmcb_control_area and vmcb_save_area
> allocated in svm_set_nested_state() are released when the function exits.
> Meanwhile, svm_set_nested_state() also have vcpu mutex held to avoid
> massive concurrency allocation, so we don't need to set GFP_KERNEL_ACCOUNT.

Hi Sean/Paolo,

Seems more patches are popping up regarding to whether to use _ACCOUNT 
for temporary memory allocation.  Could we have a definitive guide on this?

As you know, one similar patch was merged and now is in upstream:

   dd103407ca315 ("KVM: X86: Remove unnecessary GFP_KERNEL_ACCOUNT for 
temporary variables")

Also see:

https://lore.kernel.org/kvm/20240715101224.90958-1-kai.huang@intel.com/T/

> 
> Signed-off-by: Yongqiang Liu <liuyongqiang13@...wei.com>
> ---
>   arch/x86/kvm/svm/nested.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 6f704c1037e5..d5314cb7dff4 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -1693,8 +1693,8 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
>   		return -EINVAL;
>   
>   	ret  = -ENOMEM;
> -	ctl  = kzalloc(sizeof(*ctl),  GFP_KERNEL_ACCOUNT);
> -	save = kzalloc(sizeof(*save), GFP_KERNEL_ACCOUNT);
> +	ctl  = kzalloc(sizeof(*ctl),  GFP_KERNEL);
> +	save = kzalloc(sizeof(*save), GFP_KERNEL);
>   	if (!ctl || !save)
>   		goto out_free;
>