Commit 216d106c authored by Brijesh Singh's avatar Brijesh Singh Committed by Borislav Petkov (AMD)
Browse files

x86/sev: Add SEV-SNP host initialization support 



The memory integrity guarantees of SEV-SNP are enforced through a new
structure called the Reverse Map Table (RMP). The RMP is a single data
structure shared across the system that contains one entry for every 4K
page of DRAM that may be used by SEV-SNP VMs. The APM Volume 2 section
on Secure Nested Paging (SEV-SNP) details a number of steps needed to
detect/enable SEV-SNP and RMP table support on the host:

 - Detect SEV-SNP support based on CPUID bit
 - Initialize the RMP table memory reported by the RMP base/end MSR
   registers and configure IOMMU to be compatible with RMP access
   restrictions
 - Set the MtrrFixDramModEn bit in SYSCFG MSR
 - Set the SecureNestedPagingEn and VMPLEn bits in the SYSCFG MSR
 - Configure IOMMU

RMP table entry format is non-architectural and it can vary by
processor. It is defined by the PPR document for each respective CPU
family. Restrict SNP support to CPU models/families which are compatible
with the current RMP table entry format to guard against any undefined
behavior when running on other system types. Future models/support will
handle this through an architectural mechanism to allow for broader
compatibility.

SNP host code depends on CONFIG_KVM_AMD_SEV config flag which may be
enabled even when CONFIG_AMD_MEM_ENCRYPT isn't set, so update the
SNP-specific IOMMU helpers used here to rely on CONFIG_KVM_AMD_SEV
instead of CONFIG_AMD_MEM_ENCRYPT.

Signed-off-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
Co-developed-by: default avatarAshish Kalra <ashish.kalra@amd.com>
Signed-off-by: default avatarAshish Kalra <ashish.kalra@amd.com>
Co-developed-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Co-developed-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Co-developed-by: default avatarMichael Roth <michael.roth@amd.com>
Signed-off-by: default avatarMichael Roth <michael.roth@amd.com>
Link: https://lore.kernel.org/r/20240126041126.1927228-5-michael.roth@amd.com
parent 04d65a9d

arch/x86/Kbuild

+2 −0
Original line number Diff line number Diff line
@@ -28,5 +28,7 @@ obj-y += net/ 


obj-$(CONFIG_KEXEC_FILE) += purgatory/



obj-y += virt/svm/



# for cleaning

subdir- += boot tools

arch/x86/include/asm/msr-index.h

+10 −1
Original line number Diff line number Diff line
@@ -599,6 +599,8 @@ 
#define MSR_AMD64_SEV_ENABLED		BIT_ULL(MSR_AMD64_SEV_ENABLED_BIT)

#define MSR_AMD64_SEV_ES_ENABLED	BIT_ULL(MSR_AMD64_SEV_ES_ENABLED_BIT)

#define MSR_AMD64_SEV_SNP_ENABLED	BIT_ULL(MSR_AMD64_SEV_SNP_ENABLED_BIT)

#define MSR_AMD64_RMP_BASE		0xc0010132

#define MSR_AMD64_RMP_END		0xc0010133



/* SNP feature bits enabled by the hypervisor */

#define MSR_AMD64_SNP_VTOM			BIT_ULL(3)
@@ -710,6 +712,13 @@ 
#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)

#define MSR_AMD64_SYSCFG_MFDM_BIT	19

#define MSR_AMD64_SYSCFG_MFDM		BIT_ULL(MSR_AMD64_SYSCFG_MFDM_BIT)



#define MSR_K8_INT_PENDING_MSG		0xc0010055

/* C1E active bits in int pending message */

#define K8_INTP_C1E_ACTIVE_MASK		0x18000000

arch/x86/include/asm/sev.h

+6 −0
Original line number Diff line number Diff line
@@ -243,4 +243,10 @@ static inline u64 snp_get_unsupported_features(u64 status) { return 0; } 
static inline u64 sev_get_status(void) { return 0; }

#endif



#ifdef CONFIG_KVM_AMD_SEV

bool snp_probe_rmptable_info(void);

#else

static inline bool snp_probe_rmptable_info(void) { return false; }

#endif



#endif

arch/x86/kernel/cpu/amd.c

+16 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <asm/delay.h>

#include <asm/debugreg.h>

#include <asm/resctrl.h>

#include <asm/sev.h>



#ifdef CONFIG_X86_64

# include <asm/mmconfig.h>
@@ -587,6 +588,21 @@ static void bsp_init_amd(struct cpuinfo_x86 *c) 
		break;

	}



	if (cpu_has(c, X86_FEATURE_SEV_SNP)) {

		/*

		 * RMP table entry format is not architectural and it can vary by processor

		 * and is defined by the per-processor PPR. Restrict SNP support on the

		 * known CPU model and family for which the RMP table entry format is

		 * currently defined for.

		 */

		if (!boot_cpu_has(X86_FEATURE_ZEN3) &&

		    !boot_cpu_has(X86_FEATURE_ZEN4) &&

		    !boot_cpu_has(X86_FEATURE_ZEN5))

			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);

		else if (!snp_probe_rmptable_info())

			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);

	}



	return;



warn:

arch/x86/virt/svm/Makefile

0 → 100644
+3 −0
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0



obj-$(CONFIG_KVM_AMD_SEV) += sev.o