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: 216d106c7ff7 ("x86/sev: Add SEV-SNP host initialization support")
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Srikanth Aithal <sraithal@amd.com>
Link: https://lore.kernel.org/r/20240327154317.29909-6-bp@alien8.de

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 07e125f32528394df24c06de44e3232eaf15e4cd..7f57382afee41754beb8164244f199e4ac30a148 100644 (file)
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -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

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 6d8677e80ddbb17c94ec7fcda9e5bae502c0dcb2..9bf17c9c29dad2e3f3c38c07253accc667cadea3 100644 (file)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -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:

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 422a4ddc2ab7c9408f1d2d21433fea7f320c6f85..7b29ebda024f4e69bc9a9326f9cecd8a86ee2abb 100644 (file)
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -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);

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 7e1e63cc48e67dcc3f3abc84362ba805fef5a93d..38ad066179d81fe7efc2b2469fbe583c12586e06 100644 (file)
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -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;

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index ae0ac12382b9278732fc89d4ef00a5f84866f8c0..3d310b473e059d8dc8af039e1567bd0b4629b418 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -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);
 
        /*

diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index cffe1157a90acfcf741b31ac216d6fd3a9ed4fd2..ab0e8448bb6eb2bfbc4fab29321cd0ddbe876f7e 100644 (file)
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -77,7 +77,7 @@ static int __mfd_enable(unsigned int cpu)
 {
        u64 val;
 
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return 0;
 
        rdmsrl(MSR_AMD64_SYSCFG, val);
@@ -98,7 +98,7 @@ static int __snp_enable(unsigned int cpu)
 {
        u64 val;
 
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return 0;
 
        rdmsrl(MSR_AMD64_SYSCFG, val);
@@ -174,11 +174,11 @@ static int __init snp_rmptable_init(void)
        u64 rmptable_size;
        u64 val;
 
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return 0;
 
        if (!amd_iommu_snp_en)
-               return 0;
+               goto nosnp;
 
        if (!probed_rmp_size)
                goto nosnp;
@@ -225,7 +225,7 @@ skip_enable:
        return 0;
 
 nosnp:
-       setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
+       cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
        return -ENOSYS;
 }
 
@@ -246,7 +246,7 @@ static struct rmpentry *__snp_lookup_rmpentry(u64 pfn, int *level)
 {
        struct rmpentry *large_entry, *entry;
 
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return ERR_PTR(-ENODEV);
 
        entry = get_rmpentry(pfn);
@@ -363,7 +363,7 @@ int psmash(u64 pfn)
        unsigned long paddr = pfn << PAGE_SHIFT;
        int ret;
 
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return -ENODEV;
 
        if (!pfn_valid(pfn))
@@ -472,7 +472,7 @@ static int rmpupdate(u64 pfn, struct rmp_state *state)
        unsigned long paddr = pfn << PAGE_SHIFT;
        int ret, level;
 
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return -ENODEV;
 
        level = RMP_TO_PG_LEVEL(state->pagesize);
@@ -558,3 +558,13 @@ void snp_leak_pages(u64 pfn, unsigned int npages)
        spin_unlock(&snp_leaked_pages_list_lock);
 }
 EXPORT_SYMBOL_GPL(snp_leak_pages);
+
+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 (cc_platform_has(CC_ATTR_HOST_SEV_SNP))
+               wbinvd();
+}

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index f44efbb89c346a8e0b72c3d262ec9213c95aab18..2102377f727b1eecac8d28423e10a3e313b38683 100644 (file)
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1090,7 +1090,7 @@ static int __sev_snp_init_locked(int *error)
        void *arg = &data;
        int cmd, rc = 0;
 
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return -ENODEV;
 
        sev = psp->sev_data;

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index e7a44929f0daf71f017ec8fe0d1b56243ab47ba5..33228c1c8980f32a5e8af323587601a4783b5b7f 100644 (file)
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3228,7 +3228,7 @@ out:
 static void iommu_snp_enable(void)
 {
 #ifdef CONFIG_KVM_AMD_SEV
-       if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+       if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
                return;
        /*
         * The SNP support requires that IOMMU must be enabled, and is
@@ -3236,12 +3236,14 @@ static void iommu_snp_enable(void)
         */
        if (no_iommu || iommu_default_passthrough()) {
                pr_err("SNP: IOMMU disabled or configured in passthrough mode, SNP cannot be supported.\n");
+               cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
                return;
        }
 
        amd_iommu_snp_en = check_feature(FEATURE_SNP);
        if (!amd_iommu_snp_en) {
                pr_err("SNP: IOMMU SNP feature not enabled, SNP cannot be supported.\n");
+               cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
                return;
        }