linux-kernel - Re: [PATCH v5 02/34] KVM: SVM: Remove the call to sev_platform

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Message-ID: <a1a912c7-b2f8-561b-c569-d74ff946c9f5@redhat.com>
Date:   Mon, 14 Dec 2020 13:29:32 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Tom Lendacky <thomas.lendacky@....com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Jim Mattson <jmattson@...gle.com>, Joerg Roedel <joro@...tes.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH v5 02/34] KVM: SVM: Remove the call to
 sev_platform_status() during setup

On 10/12/20 18:09, Tom Lendacky wrote:
> From: Tom Lendacky <thomas.lendacky@....com>
> 
> When both KVM support and the CCP driver are built into the kernel instead
> of as modules, KVM initialization can happen before CCP initialization. As
> a result, sev_platform_status() will return a failure when it is called
> from sev_hardware_setup(), when this isn't really an error condition.
> 
> Since sev_platform_status() doesn't need to be called at this time anyway,
> remove the invocation from sev_hardware_setup().
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>   arch/x86/kvm/svm/sev.c | 22 +---------------------
>   1 file changed, 1 insertion(+), 21 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index c0b14106258a..a4ba5476bf42 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1127,9 +1127,6 @@ void sev_vm_destroy(struct kvm *kvm)
>   
>   int __init sev_hardware_setup(void)
>   {
> -	struct sev_user_data_status *status;
> -	int rc;
> -
>   	/* Maximum number of encrypted guests supported simultaneously */
>   	max_sev_asid = cpuid_ecx(0x8000001F);
>   
> @@ -1148,26 +1145,9 @@ int __init sev_hardware_setup(void)
>   	if (!sev_reclaim_asid_bitmap)
>   		return 1;
>   
> -	status = kmalloc(sizeof(*status), GFP_KERNEL);
> -	if (!status)
> -		return 1;
> -
> -	/*
> -	 * Check SEV platform status.
> -	 *
> -	 * PLATFORM_STATUS can be called in any state, if we failed to query
> -	 * the PLATFORM status then either PSP firmware does not support SEV
> -	 * feature or SEV firmware is dead.
> -	 */
> -	rc = sev_platform_status(status, NULL);
> -	if (rc)
> -		goto err;
> -
>   	pr_info("SEV supported\n");
>   
> -err:
> -	kfree(status);
> -	return rc;
> +	return 0;
>   }
>   
>   void sev_hardware_teardown(void)
> 

Queued with Cc: stable.

Note that sev_platform_status now can become static within 
drivers/crypto/ccp/sev-dev.c.

Paolo