linux-kernel - Re: [PATCH 3/3] x86/kvm: Handle all MCA banks

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: <20180622181603.GB5549@flask>
Date:   Fri, 22 Jun 2018 20:16:04 +0200
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     KVM <kvm@...r.kernel.org>, Joerg Roedel <joro@...tes.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Tony Luck <tony.luck@...el.com>,
        Yazen Ghannam <Yazen.Ghannam@....com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] x86/kvm: Handle all MCA banks

2018-06-22 11:51+0200, Borislav Petkov:
> From: Borislav Petkov <bp@...e.de>
> 
> Extend the range of MCA banks which get passed to set/get_msr_mce() to
> include all the MSRs of the last bank too.
> 
> Signed-off-by: Borislav Petkov <bp@...e.de>
> ---
>  arch/x86/kvm/x86.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 80452b0f0e8c..a7d344823356 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2466,7 +2466,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>  
>  	case MSR_IA32_MCG_CTL:
>  	case MSR_IA32_MCG_STATUS:
> -	case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1:
> +	case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_MISC(KVM_MAX_MCE_BANKS) - 1:

It was correct before.  We have 32 banks (KVM_MAX_MCE_BANKS), so the
last useable has index 31 and the "- 1" is going to roll over from first
MSR of bank 32 to the last MSR of the last bank.

Another way of writing it would be:

 case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_MISC(KVM_MAX_MCE_BANKS - 1):

>  		return set_msr_mce(vcpu, msr_info);
>  
>  	case MSR_K7_PERFCTR0 ... MSR_K7_PERFCTR3:
> @@ -2588,9 +2588,10 @@ static int get_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
>  	case MSR_IA32_MCG_STATUS:
>  		data = vcpu->arch.mcg_status;
>  		break;
> +
>  	default:
>  		if (msr >= MSR_IA32_MC0_CTL &&
> -		    msr < MSR_IA32_MCx_CTL(bank_num)) {
> +		    msr < MSR_IA32_MCx_MISC(bank_num)) {

Similar logic here.

I think it would be best just to keep the current code,

thanks.