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

Borislav Petkov
2021-09-24T08:58:25Z

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.