linux-kernel - Re: [PATCH v2 0/8] ccp: KVM: SVM: Use stack for SEV command buffers

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Message-ID: <1932d295-5e16-ebb6-b25a-5957f5d7d3ea@redhat.com>
Date:   Sat, 17 Apr 2021 14:47:17 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Borislav Petkov <bp@...e.de>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Subject: Re: [PATCH v2 0/8] ccp: KVM: SVM: Use stack for SEV command buffers

On 07/04/21 00:49, Sean Christopherson wrote:
> This series teaches __sev_do_cmd_locked() to gracefully handle vmalloc'd
> command buffers by copying _all_ incoming data pointers to an internal
> buffer before sending the command to the PSP.  The SEV driver and KVM are
> then converted to use the stack for all command buffers.
> 
> Tested everything except sev_ioctl_do_pek_import(), I don't know anywhere
> near enough about the PSP to give it the right input.
> 
> v2:
>    - Rebase to kvm/queue, commit f96be2deac9b ("KVM: x86: Support KVM VMs
>      sharing SEV context").
>    - Unconditionally copy @data to the internal buffer. [Christophe, Brijesh]
>    - Allocate a full page for the buffer. [Brijesh]
>    - Drop one set of the "!"s. [Christophe]
>    - Use virt_addr_valid() instead of is_vmalloc_addr() for the temporary
>      patch (definitely feel free to drop the patch if it's not worth
>      backporting). [Christophe]
>    - s/intput/input/. [Tom]
>    - Add a patch to free "sev" if init fails.  This is not strictly
>      necessary (I think; I suck horribly when it comes to the driver
>      framework).   But it felt wrong to not free cmd_buf on failure, and
>      even more wrong to free cmd_buf but not sev.
> 
> v1:
>    - https://lkml.kernel.org/r/20210402233702.3291792-1-seanjc@google.com
> 
> Sean Christopherson (8):
>    crypto: ccp: Free SEV device if SEV init fails
>    crypto: ccp: Detect and reject "invalid" addresses destined for PSP
>    crypto: ccp: Reject SEV commands with mismatching command buffer
>    crypto: ccp: Play nice with vmalloc'd memory for SEV command structs
>    crypto: ccp: Use the stack for small SEV command buffers
>    crypto: ccp: Use the stack and common buffer for status commands
>    crypto: ccp: Use the stack and common buffer for INIT command
>    KVM: SVM: Allocate SEV command structures on local stack
> 
>   arch/x86/kvm/svm/sev.c       | 262 +++++++++++++----------------------
>   drivers/crypto/ccp/sev-dev.c | 197 +++++++++++++-------------
>   drivers/crypto/ccp/sev-dev.h |   4 +-
>   3 files changed, 196 insertions(+), 267 deletions(-)
> 

Queued, thanks.

Paolo