linux-kernel - Re: [PATCH Part1 RFC v3 07/22] x86/sev: Add a helper for the PVALIDATE instruction

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Date:   Mon, 7 Jun 2021 17:35:18 +0200
From:   Borislav Petkov <bp@...en8.de>
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,
        linux-crypto@...r.kernel.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>,
        Wanpeng Li <wanpengli@...cent.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>, tony.luck@...el.com,
        npmccallum@...hat.com
Subject: Re: [PATCH Part1 RFC v3 07/22] x86/sev: Add a helper for the
 PVALIDATE instruction

On Wed, Jun 02, 2021 at 09:04:01AM -0500, Brijesh Singh wrote:
> +static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate)
> +{
> +	bool no_rmpupdate;
> +	int rc;

>From a previous review:

Please put over the opcode bytes line:

        /* "pvalidate" mnemonic support in binutils 2.36 and newer */

> +	asm volatile(".byte 0xF2, 0x0F, 0x01, 0xFF\n\t"
> +		     CC_SET(c)
> +		     : CC_OUT(c) (no_rmpupdate), "=a"(rc)
> +		     : "a"(vaddr), "c"(rmp_psize), "d"(validate)
> +		     : "memory", "cc");
> +
> +	if (no_rmpupdate)
> +		return PVALIDATE_FAIL_NOUPDATE;
> +
> +	return rc;
> +}

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette