linux-kernel - Re: [PATCH v7 02/45] x86/sev: detect/setup SEV/SME features earlier in boot

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Message-ID: <Ya6hEPTkuUqhBn+z@dt>
Date:   Mon, 6 Dec 2021 17:47:28 -0600
From:   Venu Busireddy <venu.busireddy@...cle.com>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Borislav Petkov <bp@...en8.de>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH v7 02/45] x86/sev: detect/setup SEV/SME features earlier
 in boot

On 2021-11-10 16:06:48 -0600, Brijesh Singh wrote:
> From: Michael Roth <michael.roth@....com>
> 
> sme_enable() handles feature detection for both SEV and SME. Future
> patches will also use it for SEV-SNP feature detection/setup, which
> will need to be done immediately after the first #VC handler is set up.
> Move it now in preparation.

The previous patch added the function sev_enable(), which has most of its
code duplicated in sme_enable(). Can sme_enable() be changed (and maybe
sev_enable() a bit) to call sev_enable() and avoid all the duplicate code?

Venu

> 
> Signed-off-by: Michael Roth <michael.roth@....com>
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  arch/x86/include/asm/setup.h | 2 +-
>  arch/x86/kernel/head64.c     | 8 ++++----
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
> index a12458a7a8d4..cee1e816fdcd 100644
> --- a/arch/x86/include/asm/setup.h
> +++ b/arch/x86/include/asm/setup.h
> @@ -50,7 +50,7 @@ extern void reserve_standard_io_resources(void);
>  extern void i386_reserve_resources(void);
>  extern unsigned long __startup_64(unsigned long physaddr, struct boot_params *bp);
>  extern unsigned long __startup_secondary_64(void);
> -extern void startup_64_setup_env(unsigned long physbase);
> +extern void startup_64_setup_env(unsigned long physbase, struct boot_params *bp);
>  extern void early_setup_idt(void);
>  extern void __init do_early_exception(struct pt_regs *regs, int trapnr);
>  
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index fc5371a7e9d1..4eb83ae7ceb8 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -163,9 +163,6 @@ unsigned long __head __startup_64(unsigned long physaddr,
>  	if (load_delta & ~PMD_PAGE_MASK)
>  		for (;;);
>  
> -	/* Activate Secure Memory Encryption (SME) if supported and enabled */
> -	sme_enable(bp);
> -
>  	/* Include the SME encryption mask in the fixup value */
>  	load_delta += sme_get_me_mask();
>  
> @@ -594,7 +591,7 @@ void early_setup_idt(void)
>  /*
>   * Setup boot CPU state needed before kernel switches to virtual addresses.
>   */
> -void __head startup_64_setup_env(unsigned long physbase)
> +void __head startup_64_setup_env(unsigned long physbase, struct boot_params *bp)
>  {
>  	/* Load GDT */
>  	startup_gdt_descr.address = (unsigned long)fixup_pointer(startup_gdt, physbase);
> @@ -606,4 +603,7 @@ void __head startup_64_setup_env(unsigned long physbase)
>  		     "movl %%eax, %%es\n" : : "a"(__KERNEL_DS) : "memory");
>  
>  	startup_64_load_idt(physbase);
> +
> +	/* Activate SEV/SME memory encryption if supported/enabled. */
> +	sme_enable(bp);
>  }
> -- 
> 2.25.1
>