linux-kernel - Re: [PATCH 12/25] x86/sgx: Add helper to update SGX

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Date:   Mon, 1 Mar 2021 08:57:06 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Kai Huang <kai.huang@...el.com>
Cc:     kvm@...r.kernel.org, linux-sgx@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, jarkko@...nel.org, luto@...nel.org,
        dave.hansen@...el.com, rick.p.edgecombe@...el.com,
        haitao.huang@...el.com, pbonzini@...hat.com, bp@...en8.de,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com
Subject: Re: [PATCH 12/25] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn
 MSRs

On Mon, Mar 01, 2021, Kai Huang wrote:
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 8c922e68274d..276220d0e4b5 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -696,6 +696,21 @@ static bool __init sgx_page_cache_init(void)
>  	return true;
>  }
>  
> +
> +/*
> + * Update the SGX_LEPUBKEYHASH MSRs to the values specified by caller.
> + * Bare-metal driver requires to update them to hash of enclave's signer
> + * before EINIT. KVM needs to update them to guest's virtual MSR values
> + * before doing EINIT from guest.
> + */
> +void sgx_update_lepubkeyhash(u64 *lepubkeyhash)
> +{
> +	int i;

Probably worth adding:

	WARN_ON_ONCE(preemptible());

> +
> +	for (i = 0; i < 4; i++)
> +		wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]);
> +}
> +
>  static int __init sgx_init(void)
>  {
>  	int ret;