Commit 0ecaefb3 authored by Borislav Petkov (AMD)'s avatar Borislav Petkov (AMD)
Browse files

x86/CPU/AMD: Track SNP host status with cc_platform_*() 



The host SNP worthiness can determined later, after alternatives have
been patched, in snp_rmptable_init() depending on cmdline options like
iommu=pt which is incompatible with SNP, for example.

Which means that one cannot use X86_FEATURE_SEV_SNP and will need to
have a special flag for that control.

Use that newly added CC_ATTR_HOST_SEV_SNP in the appropriate places.

Move kdump_sev_callback() to its rightful place, while at it.

Fixes: 216d106c ("x86/sev: Add SEV-SNP host initialization support")
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Tested-by: default avatarSrikanth Aithal <sraithal@amd.com>
Link: https://lore.kernel.org/r/20240327154317.29909-6-bp@alien8.de
parent bc6f707f

arch/x86/include/asm/sev.h

+2 −2
Original line number Diff line number Diff line
@@ -228,7 +228,6 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn 
void snp_accept_memory(phys_addr_t start, phys_addr_t end);

u64 snp_get_unsupported_features(u64 status);

u64 sev_get_status(void);

void kdump_sev_callback(void);

void sev_show_status(void);

#else

static inline void sev_es_ist_enter(struct pt_regs *regs) { }
@@ -258,7 +257,6 @@ static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *in 
static inline void snp_accept_memory(phys_addr_t start, phys_addr_t end) { }

static inline u64 snp_get_unsupported_features(u64 status) { return 0; }

static inline u64 sev_get_status(void) { return 0; }

static inline void kdump_sev_callback(void) { }

static inline void sev_show_status(void) { }

#endif
@@ -270,6 +268,7 @@ int psmash(u64 pfn); 
int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 asid, bool immutable);

int rmp_make_shared(u64 pfn, enum pg_level level);

void snp_leak_pages(u64 pfn, unsigned int npages);

void kdump_sev_callback(void);

#else

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

static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; }
@@ -282,6 +281,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 as 
}

static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; }

static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}

static inline void kdump_sev_callback(void) { }

#endif



#endif

arch/x86/kernel/cpu/amd.c

+23 −15
Original line number Diff line number Diff line
@@ -345,6 +345,28 @@ static void srat_detect_node(struct cpuinfo_x86 *c) 
#endif

}



static void bsp_determine_snp(struct cpuinfo_x86 *c)

{

#ifdef CONFIG_ARCH_HAS_CC_PLATFORM

	cc_vendor = CC_VENDOR_AMD;



	if (cpu_has(c, X86_FEATURE_SEV_SNP)) {

		/*

		 * RMP table entry format is not architectural and is defined by the

		 * per-processor PPR. Restrict SNP support on the known CPU models

		 * for which the RMP table entry format is currently defined for.

		 */

		if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&

		    c->x86 >= 0x19 && snp_probe_rmptable_info()) {

			cc_platform_set(CC_ATTR_HOST_SEV_SNP);

		} else {

			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);

			cc_platform_clear(CC_ATTR_HOST_SEV_SNP);

		}

	}

#endif

}



static void bsp_init_amd(struct cpuinfo_x86 *c)

{

	if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) {
@@ -452,21 +474,7 @@ 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);

	}



	bsp_determine_snp(c);

	return;



warn:

arch/x86/kernel/cpu/mtrr/generic.c

+1 −1
Original line number Diff line number Diff line
@@ -108,7 +108,7 @@ static inline void k8_check_syscfg_dram_mod_en(void) 
	      (boot_cpu_data.x86 >= 0x0f)))

		return;



	if (cpu_feature_enabled(X86_FEATURE_SEV_SNP))

	if (cc_platform_has(CC_ATTR_HOST_SEV_SNP))

		return;



	rdmsr(MSR_AMD64_SYSCFG, lo, hi);

arch/x86/kernel/sev.c

+0 −10
Original line number Diff line number Diff line
@@ -2284,16 +2284,6 @@ static int __init snp_init_platform_device(void) 
}

device_initcall(snp_init_platform_device);



void kdump_sev_callback(void)

{

	/*

	 * Do wbinvd() on remote CPUs when SNP is enabled in order to

	 * safely do SNP_SHUTDOWN on the local CPU.

	 */

	if (cpu_feature_enabled(X86_FEATURE_SEV_SNP))

		wbinvd();

}



void sev_show_status(void)

{

	int i;

arch/x86/kvm/svm/sev.c

+1 −1
Original line number Diff line number Diff line
@@ -3174,7 +3174,7 @@ struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu) 
	unsigned long pfn;

	struct page *p;



	if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))

	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))

		return alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);



	/*