linux-kernel - Re: [PATCH Part2 v5 03/45] x86/sev: Add the host SEV-SNP initialization support

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Message-ID: <YU2TGxrpwMD8QLnk@zn.tnic>
Date:   Fri, 24 Sep 2021 10:58:03 +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-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>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>, tony.luck@...el.com,
        marcorr@...gle.com, sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH Part2 v5 03/45] x86/sev: Add the host SEV-SNP
 initialization support

On Fri, Aug 20, 2021 at 10:58:36AM -0500, Brijesh Singh wrote:
> @@ -542,6 +544,10 @@
>  #define MSR_AMD64_SYSCFG		0xc0010010
>  #define MSR_AMD64_SYSCFG_MEM_ENCRYPT_BIT	23
>  #define MSR_AMD64_SYSCFG_MEM_ENCRYPT	BIT_ULL(MSR_AMD64_SYSCFG_MEM_ENCRYPT_BIT)
> +#define MSR_AMD64_SYSCFG_SNP_EN_BIT		24
> +#define MSR_AMD64_SYSCFG_SNP_EN		BIT_ULL(MSR_AMD64_SYSCFG_SNP_EN_BIT)
> +#define MSR_AMD64_SYSCFG_SNP_VMPL_EN_BIT	25
> +#define MSR_AMD64_SYSCFG_SNP_VMPL_EN	BIT_ULL(MSR_AMD64_SYSCFG_SNP_VMPL_EN_BIT)

While you're here, move all defines that belong to that MSR which
we decided it is architectural after all, above the definition of
MSR_AMD64_NB_CFG above.

>  #define MSR_K8_INT_PENDING_MSG		0xc0010055
>  /* C1E active bits in int pending message */
>  #define K8_INTP_C1E_ACTIVE_MASK		0x18000000
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index ab17c93634e9..7936c8139c74 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -24,6 +24,8 @@
>  #include <linux/sev-guest.h>
>  #include <linux/platform_device.h>
>  #include <linux/io.h>
> +#include <linux/cpumask.h>
> +#include <linux/iommu.h>
>  
>  #include <asm/cpu_entry_area.h>
>  #include <asm/stacktrace.h>
> @@ -40,11 +42,19 @@
>  #include <asm/efi.h>
>  #include <asm/cpuid.h>
>  #include <asm/setup.h>
> +#include <asm/apic.h>
> +#include <asm/iommu.h>
>  
>  #include "sev-internal.h"
>  
>  #define DR7_RESET_VALUE        0x400
>  
> +/*
> + * The first 16KB from the RMP_BASE is used by the processor for the

s/for the/for/

> + * bookkeeping, the range need to be added during the RMP entry lookup.

s/need/needs/ ... s/during the/during /

> + */
> +#define RMPTABLE_CPU_BOOKKEEPING_SZ	0x4000

Too long: just call it RMP_BASE_OFFSET.

> +static bool get_rmptable_info(u64 *start, u64 *len)
> +{
> +	u64 calc_rmp_sz, rmp_sz, rmp_base, rmp_end, nr_pages;
> +
> +	rdmsrl(MSR_AMD64_RMP_BASE, rmp_base);
> +	rdmsrl(MSR_AMD64_RMP_END, rmp_end);
> +
> +	if (!rmp_base || !rmp_end) {
> +		pr_info("Memory for the RMP table has not been reserved by BIOS\n");
> +		return false;
> +	}
> +
> +	rmp_sz = rmp_end - rmp_base + 1;
> +
> +	/*
> +	 * Calculate the amount the memory that must be reserved by the BIOS to
> +	 * address the full system RAM. The reserved memory should also cover the
> +	 * RMP table itself.
> +	 *
> +	 * See PPR Family 19h Model 01h, Revision B1 section 2.1.5.2 for more
> +	 * information on memory requirement.
> +	 */
> +	nr_pages = totalram_pages();
> +	calc_rmp_sz = (((rmp_sz >> PAGE_SHIFT) + nr_pages) << 4) + RMPTABLE_CPU_BOOKKEEPING_SZ;

use totalram_pages() directly here - nr_pages is assigned to only once.

> +
> +	if (calc_rmp_sz > rmp_sz) {
> +		pr_info("Memory reserved for the RMP table does not cover full system RAM (expected 0x%llx got 0x%llx)\n",
> +			calc_rmp_sz, rmp_sz);
> +		return false;
> +	}
> +
> +	*start = rmp_base;
> +	*len = rmp_sz;
> +
> +	pr_info("RMP table physical address 0x%016llx - 0x%016llx\n", rmp_base, rmp_end);

		"RMP table physical address range: [ ... - ... ]\n", ...

...

> +/*
> + * This must be called after the PCI subsystem. This is because before enabling
> + * the SNP feature we need to ensure that IOMMU supports the SEV-SNP feature.

"... it needs to be ensured that... "

> + * The iommu_sev_snp_support() is used for checking the feature, and it is
> + * available after subsys_initcall().
> + */
> +fs_initcall(snp_rmptable_init);
> -- 
> 2.17.1
> 

-- 
Regards/Gruss,
    Boris.

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