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

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Message-ID: <26bbc4fb-3300-2c0d-61e9-79e88457ce94@amd.com>
Date:   Wed, 7 Apr 2021 12:16:49 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>
Cc:     brijesh.singh@....com, 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 4/6/21 5:49 PM, 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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.kernel.org%2Fr%2F20210402233702.3291792-1-seanjc%40google.com&amp;data=04%7C01%7Cbrijesh.singh%40amd.com%7C051db746fc2048e06acb08d8f94e527b%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637533462083069551%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=bbNHBXMO1RWh8i4siTYkv4P92Ph5C7SnAZ3uTPsxgvg%3D&amp;reserved=0
>
> 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(-)
>

Thanks Sean.

Reviewed-by: Brijesh Singh <brijesh.singh@....com>