linux-kernel - Re: [PATCH v12 26/29] KVM: SEV: Provide support for SNP_GUEST

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Date: Wed, 10 Apr 2024 17:14:27 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Michael Roth <michael.roth@....com>, kvm@...r.kernel.org
Cc: linux-coco@...ts.linux.dev, linux-mm@...ck.org,
 linux-crypto@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org,
 tglx@...utronix.de, mingo@...hat.com, jroedel@...e.de, hpa@...or.com,
 ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
 vkuznets@...hat.com, jmattson@...gle.com, luto@...nel.org,
 dave.hansen@...ux.intel.com, slp@...hat.com, pgonda@...gle.com,
 peterz@...radead.org, srinivas.pandruvada@...ux.intel.com,
 rientjes@...gle.com, dovmurik@...ux.ibm.com, tobin@....com, bp@...en8.de,
 vbabka@...e.cz, kirill@...temov.name, ak@...ux.intel.com,
 tony.luck@...el.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
 alpergun@...gle.com, jarkko@...nel.org, ashish.kalra@....com,
 nikunj.dadhania@....com, pankaj.gupta@....com, liam.merwick@...cle.com,
 Brijesh Singh <brijesh.singh@....com>, Alexey Kardashevskiy <aik@....com>
Subject: Re: [PATCH v12 26/29] KVM: SEV: Provide support for SNP_GUEST_REQUEST
 NAE event

On 3/29/24 17:58, Michael Roth wrote:
> From: Brijesh Singh <brijesh.singh@....com>
> 
> Version 2 of GHCB specification added support for the SNP Guest Request
> Message NAE event. The event allows for an SEV-SNP guest to make
> requests to the SEV-SNP firmware through hypervisor using the
> SNP_GUEST_REQUEST API defined in the SEV-SNP firmware specification.
> 
> This is used by guests primarily to request attestation reports from
> firmware. There are other request types are available as well, but the
> specifics of what guest requests are being made are opaque to the
> hypervisor, which only serves as a proxy for the guest requests and
> firmware responses.
> 
> Implement handling for these events.
> 
> Co-developed-by: Alexey Kardashevskiy <aik@....com>
> Signed-off-by: Alexey Kardashevskiy <aik@....com>
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>

You need to add a Co-developed-by: for Asish here.

> [mdr: ensure FW command failures are indicated to guest, drop extended
>   request handling to be re-written as separate patch, massage commit]
> Signed-off-by: Michael Roth <michael.roth@....com>

One minor comment below should another version be required, otherwise:

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

> ---
>   arch/x86/kvm/svm/sev.c         | 83 ++++++++++++++++++++++++++++++++++
>   include/uapi/linux/sev-guest.h |  9 ++++
>   2 files changed, 92 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 658116537f3f..f56f04553e81 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c

>   
> +static bool snp_setup_guest_buf(struct kvm *kvm, struct sev_data_snp_guest_request *data,
> +				gpa_t req_gpa, gpa_t resp_gpa)
> +{
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	kvm_pfn_t req_pfn, resp_pfn;
> +
> +	if (!IS_ALIGNED(req_gpa, PAGE_SIZE) || !IS_ALIGNED(resp_gpa, PAGE_SIZE))

Minor, but you can use PAGE_ALIGNED() here.

Thanks,
Tom

> +		return false;