linux-kernel - Re: [PATCH for 5.4] Fix unsynchronized access to sev members through svm_register_enc

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Message-ID: <YCU8+Piht0VZzrzx@kroah.com>
Date:   Thu, 11 Feb 2021 15:19:36 +0100
From:   Greg KH <greg@...ah.com>
To:     Peter Gonda <pgonda@...gle.com>
Cc:     stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>,
        Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH for 5.4] Fix unsynchronized access to sev members through
 svm_register_enc_region

On Mon, Feb 08, 2021 at 08:48:55AM -0800, Peter Gonda wrote:
> commit 19a23da53932bc8011220bd8c410cb76012de004 upstream.
> 
> Grab kvm->lock before pinning memory when registering an encrypted
> region; sev_pin_memory() relies on kvm->lock being held to ensure
> correctness when checking and updating the number of pinned pages.
> 
> Add a lockdep assertion to help prevent future regressions.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: Brijesh Singh <brijesh.singh@....com>
> Cc: Sean Christopherson <seanjc@...gle.com>
> Cc: x86@...nel.org
> Cc: kvm@...r.kernel.org
> Cc: stable@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Fixes: 1e80fdc09d12 ("KVM: SVM: Pin guest memory when SEV is active")
> Signed-off-by: Peter Gonda <pgonda@...gle.com>
> 
> V2
>  - Fix up patch description
>  - Correct file paths svm.c -> sev.c
>  - Add unlock of kvm->lock on sev_pin_memory error
> 
> V1
>  - https://lore.kernel.org/kvm/20210126185431.1824530-1-pgonda@google.com/
> 
> Message-Id: <20210127161524.2832400-1-pgonda@...gle.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/kvm/svm.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)a

Both backports now queued up, thanks.

greg k-h