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]
Date:   Fri, 15 Oct 2021 11:11:19 -0500
From:   Brijesh Singh <>
To:     Sean Christopherson <>
Cc:,,,,,,, Thomas Gleixner <>,
        Ingo Molnar <>, Joerg Roedel <>,
        Tom Lendacky <>,
        "H. Peter Anvin" <>, Ard Biesheuvel <>,
        Paolo Bonzini <>,
        Vitaly Kuznetsov <>,
        Wanpeng Li <>,
        Jim Mattson <>,
        Andy Lutomirski <>,
        Dave Hansen <>,
        Sergio Lopez <>, Peter Gonda <>,
        Peter Zijlstra <>,
        Srinivas Pandruvada <>,
        David Rientjes <>,
        Dov Murik <>,
        Tobin Feldman-Fitzthum <>,
        Borislav Petkov <>,
        Michael Roth <>,
        Vlastimil Babka <>,
        "Kirill A . Shutemov" <>,
        Andi Kleen <>,,,
Subject: Re: [PATCH Part2 v5 34/45] KVM: SVM: Do not use long-lived GHCB map
 while setting scratch area

On 10/13/21 2:20 PM, Sean Christopherson wrote:
> On Fri, Aug 20, 2021, Brijesh Singh wrote:
>> The setup_vmgexit_scratch() function may rely on a long-lived GHCB
>> mapping if the GHCB shared buffer area was used for the scratch area.
>> In preparation for eliminating the long-lived GHCB mapping, always
>> allocate a buffer for the scratch area so it can be accessed without
>> the GHCB mapping.
> Would it make sense to post this patch and the next (Remove the long-lived GHCB
> host map) in a separate mini-series?  It's needed for SNP, but AFAICT there's
> nothing that depends on SNP.  Getting this merged ahead of time would reduce the
> size of the SNP series by a smidge.

While testing with random configs, I am seeing some might_sleep() warns.
This is happening mainly because during the vmrun the GHCB is accessed
with preempt disabled. The kvm_vcpu_map() -> kmap() reports the warning.
I am leaning towards creating a cache on the vmgexit and use that cache
instead of the doing a kmap() on every access. Does that sound okay to you ?


Powered by blists - more mailing lists