linux-kernel - RE: [PATCH Part2 v6 03/49] x86/sev: Add the host SEV-SNP initialization support

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Message-ID: <SN6PR12MB2767C6D128C991F86B40057C8EB39@SN6PR12MB2767.namprd12.prod.outlook.com>
Date:   Tue, 21 Jun 2022 17:59:44 +0000
From:   "Kalra, Ashish" <Ashish.Kalra@....com>
To:     Peter Gonda <pgonda@...gle.com>
CC:     the arch/x86 maintainers <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        "linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        "Lendacky, Thomas" <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 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>,
        "Roth, Michael" <Michael.Roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>, Marc Orr <marcorr@...gle.com>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Alper Gun <alpergun@...gle.com>,
        "Dr. David Alan Gilbert" <dgilbert@...hat.com>,
        "jarkko@...nel.org" <jarkko@...nel.org>
Subject: RE: [PATCH Part2 v6 03/49] x86/sev: Add the host SEV-SNP
 initialization support

[Public]

Hello Peter,

>> +static __init int __snp_rmptable_init(void) {
>> +       u64 rmp_base, sz;
>> +       void *start;
>> +       u64 val;
>> +
>> +       if (!get_rmptable_info(&rmp_base, &sz))
>> +               return 1;
>> +
>> +       start = memremap(rmp_base, sz, MEMREMAP_WB);
>> +       if (!start) {
>> +               pr_err("Failed to map RMP table 0x%llx+0x%llx\n", rmp_base, sz);
>> +               return 1;
>> +       }
>> +
>> +       /*
>> +        * Check if SEV-SNP is already enabled, this can happen if we are coming from
>> +        * kexec boot.
>> +        */
>> +       rdmsrl(MSR_AMD64_SYSCFG, val);
>> +       if (val & MSR_AMD64_SYSCFG_SNP_EN)
>> +               goto skip_enable;
>> +
>> +       /* Initialize the RMP table to zero */
>> +       memset(start, 0, sz);
>> +
>> +       /* Flush the caches to ensure that data is written before SNP is enabled. */
>> +       wbinvd_on_all_cpus();
>> +
>> +       /* Enable SNP on all CPUs. */
>> +       on_each_cpu(snp_enable, NULL, 1);
>> +
>> +skip_enable:
>> +       rmptable_start = (unsigned long)start;
>> +       rmptable_end = rmptable_start + sz;

> Since in get_rmptable_info() `rmp_sz = rmp_end - rmp_base + 1;` should this be `rmptable_end = rmptable_start + sz - 1;`?

Yes, it should be.

Thanks,
Ashish