- Remove redundant GHCB initialization guards in the SEV page state and SVSM

call paths now that the GHCB helpers handle early-boot fallback internally
 
 - Skip SNP initialization in the CCP driver immediately when the preparation
   step fails rather than proceeding to an operation that will certainly fail
 
 - Abort SNP preparation and return an error when not all CPUs are online,
   since the firmware enforces that every CPU enables SNP and will fail init if
   not
 
 - Simplify the VMM communication exception entry path by replacing separate
   kernel and user mode macros with a single handler that dispatches based on
   the current privilege level
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Merge tag 'x86_sev_for_v7.2_rc1' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

Pull x86 SEV updates from Borislav Petkov:

 - Remove redundant GHCB initialization guards in the SEV page state and
   SVSM call paths now that the GHCB helpers handle early-boot fallback
   internally

 - Skip SNP initialization in the CCP driver immediately when the
   preparation step fails rather than proceeding to an operation that
   will certainly fail

 - Abort SNP preparation and return an error when not all CPUs are
   online, since the firmware enforces that every CPU enables SNP and
   will fail init if not

 - Simplify the VMM communication exception entry path by replacing
   separate kernel and user mode macros with a single handler that
   dispatches based on the current privilege level

* tag 'x86_sev_for_v7.2_rc1' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip:
  x86/sev: Remove redundant ghcbs_initialized checks around __sev_{get,put}_ghcb()
  crypto/ccp: Skip SNP_INIT if preparation fails
  x86/sev: Do not initialize SNP if missing CPUs
  x86/entry: Zap the #VC entry user and kernel macros

arch/x86/coco/sev/core.c

@@ -367,17 +367,13 @@ static unsigned long __set_pages_state(struct snp_psc_desc *data, unsigned long
 
 	local_irq_save(flags);
 
-	if (sev_cfg.ghcbs_initialized)
-		ghcb = __sev_get_ghcb(&state);
-	else
-		ghcb = boot_ghcb;
+	ghcb = __sev_get_ghcb(&state);
 
 	/* Invoke the hypervisor to perform the page state changes */
 	if (!ghcb || vmgexit_psc(ghcb, data))
 		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC);
 
-	if (sev_cfg.ghcbs_initialized)
-		__sev_put_ghcb(&state);
+	__sev_put_ghcb(&state);
 
 	local_irq_restore(flags);
 

arch/x86/coco/sev/internal.h

@@ -70,6 +70,9 @@ void svsm_pval_pages(struct snp_psc_desc *desc);
 int svsm_perform_call_protocol(struct svsm_call *call);
 bool snp_svsm_vtpm_probe(void);
 
+noinstr void kernel_exc_vmm_communication(struct pt_regs *regs, unsigned long error_code);
+noinstr void user_exc_vmm_communication(struct pt_regs *regs, unsigned long error_code);
+
 static inline u64 sev_es_rd_ghcb_msr(void)
 {
 	return native_rdmsrq(MSR_AMD64_SEV_ES_GHCB);

arch/x86/coco/sev/noinstr.c

@@ -121,8 +121,10 @@ noinstr struct ghcb *__sev_get_ghcb(struct ghcb_state *state)
 
 	WARN_ON(!irqs_disabled());
 
-	if (!sev_cfg.ghcbs_initialized)
+	if (!sev_cfg.ghcbs_initialized) {
+		state->ghcb = NULL;
 		return boot_ghcb;
+	}
 
 	data = this_cpu_read(runtime_data);
 	ghcb = &data->ghcb_page;

arch/x86/coco/sev/svsm.c

@@ -74,20 +74,14 @@ int svsm_perform_call_protocol(struct svsm_call *call)
 
 	flags = native_local_irq_save();
 
-	if (sev_cfg.ghcbs_initialized)
-		ghcb = __sev_get_ghcb(&state);
-	else if (boot_ghcb)
-		ghcb = boot_ghcb;
-	else
-		ghcb = NULL;
+	ghcb = __sev_get_ghcb(&state);
 
 	do {
 		ret = ghcb ? svsm_perform_ghcb_protocol(ghcb, call)
 			   : __pi_svsm_perform_msr_protocol(call);
 	} while (ret == -EAGAIN);
 
-	if (sev_cfg.ghcbs_initialized)
-		__sev_put_ghcb(&state);
+	__sev_put_ghcb(&state);
 
 	native_local_irq_restore(flags);
 

arch/x86/coco/sev/vc-handle.c

@@ -954,7 +954,7 @@ static __always_inline bool vc_is_db(unsigned long error_code)
  * Runtime #VC exception handler when raised from kernel mode. Runs in NMI mode
  * and will panic when an error happens.
  */
-DEFINE_IDTENTRY_VC_KERNEL(exc_vmm_communication)
+noinstr void kernel_exc_vmm_communication(struct pt_regs *regs, unsigned long error_code)
 {
 	irqentry_state_t irq_state;
 
@@ -1006,7 +1006,7 @@ DEFINE_IDTENTRY_VC_KERNEL(exc_vmm_communication)
  * Runtime #VC exception handler when raised from user mode. Runs in IRQ mode
  * and will kill the current task with SIGBUS when an error happens.
  */
-DEFINE_IDTENTRY_VC_USER(exc_vmm_communication)
+noinstr void user_exc_vmm_communication(struct pt_regs *regs, unsigned long error_code)
 {
 	/*
 	 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
@@ -1032,6 +1032,14 @@ DEFINE_IDTENTRY_VC_USER(exc_vmm_communication)
 	irqentry_exit_to_user_mode(regs);
 }
 
+DEFINE_IDTENTRY_RAW_ERRORCODE(exc_vmm_communication)
+{
+	if (user_mode(regs))
+		return user_exc_vmm_communication(regs, error_code);
+	else
+		return kernel_exc_vmm_communication(regs, error_code);
+}
+
 bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
 {
 	unsigned long exit_code = regs->orig_ax;

arch/x86/entry/entry_64.S

@@ -492,7 +492,7 @@ SYM_CODE_START(\asmsym)
 
 	movq	%rsp, %rdi		/* pt_regs pointer */
 
-	call	kernel_\cfunc
+	call	\cfunc
 
 	/*
 	 * No need to switch back to the IST stack. The current stack is either
@@ -503,7 +503,7 @@ SYM_CODE_START(\asmsym)
 
 	/* Switch to the regular task stack */
 .Lfrom_usermode_switch_stack_\@:
-	idtentry_body user_\cfunc, has_error_code=1
+	idtentry_body \cfunc, has_error_code=1
 
 _ASM_NOKPROBE(\asmsym)
 SYM_CODE_END(\asmsym)

arch/x86/entry/entry_fred.c

@@ -177,16 +177,6 @@ static noinstr void fred_extint(struct pt_regs *regs)
 	}
 }
 
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-noinstr void exc_vmm_communication(struct pt_regs *regs, unsigned long error_code)
-{
-	if (user_mode(regs))
-		return user_exc_vmm_communication(regs, error_code);
-	else
-		return kernel_exc_vmm_communication(regs, error_code);
-}
-#endif
-
 static noinstr void fred_hwexc(struct pt_regs *regs, unsigned long error_code)
 {
 	/* Optimize for #PF. That's the only exception which matters performance wise */

arch/x86/include/asm/idtentry.h

@@ -340,17 +340,14 @@ static __always_inline void __##func(struct pt_regs *regs)
 	__visible void noist_##func(struct pt_regs *regs)
 
 /**
- * DECLARE_IDTENTRY_VC - Declare functions for the VC entry point
+ * DECLARE_IDTENTRY_VC - Declare a function for the VC entry point
  * @vector:	Vector number (ignored for C)
  * @func:	Function name of the entry point
  *
- * Maps to DECLARE_IDTENTRY_RAW_ERRORCODE, but declares also the
- * safe_stack C handler.
+ * Maps to DECLARE_IDTENTRY_RAW_ERRORCODE.
  */
 #define DECLARE_IDTENTRY_VC(vector, func)				\
-	DECLARE_IDTENTRY_RAW_ERRORCODE(vector, func);			\
-	__visible noinstr void kernel_##func(struct pt_regs *regs, unsigned long error_code);	\
-	__visible noinstr void   user_##func(struct pt_regs *regs, unsigned long error_code)
+	DECLARE_IDTENTRY_RAW_ERRORCODE(vector, func);
 
 /**
  * DEFINE_IDTENTRY_IST - Emit code for IST entry points
@@ -391,26 +388,6 @@ static __always_inline void __##func(struct pt_regs *regs)
 #define DEFINE_IDTENTRY_DF(func)					\
 	DEFINE_IDTENTRY_RAW_ERRORCODE(func)
 
-/**
- * DEFINE_IDTENTRY_VC_KERNEL - Emit code for VMM communication handler
- *			       when raised from kernel mode
- * @func:	Function name of the entry point
- *
- * Maps to DEFINE_IDTENTRY_RAW_ERRORCODE
- */
-#define DEFINE_IDTENTRY_VC_KERNEL(func)				\
-	DEFINE_IDTENTRY_RAW_ERRORCODE(kernel_##func)
-
-/**
- * DEFINE_IDTENTRY_VC_USER - Emit code for VMM communication handler
- *			     when raised from user mode
- * @func:	Function name of the entry point
- *
- * Maps to DEFINE_IDTENTRY_RAW_ERRORCODE
- */
-#define DEFINE_IDTENTRY_VC_USER(func)				\
-	DEFINE_IDTENTRY_RAW_ERRORCODE(user_##func)
-
 #else	/* CONFIG_X86_64 */
 
 /**

arch/x86/include/asm/sev.h

@@ -661,7 +661,7 @@ static inline void snp_leak_pages(u64 pfn, unsigned int pages)
 {
 	__snp_leak_pages(pfn, pages, true);
 }
-void snp_prepare(void);
+int snp_prepare(void);
 void snp_shutdown(void);
 #else
 static inline bool snp_probe_rmptable_info(void) { return false; }
@@ -679,7 +679,7 @@ static inline void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp)
 static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}
 static inline void kdump_sev_callback(void) { }
 static inline void snp_fixup_e820_tables(void) {}
-static inline void snp_prepare(void) {}
+static inline int snp_prepare(void) { return -ENODEV; }
 static inline void snp_shutdown(void) {}
 #endif
 

arch/x86/virt/svm/sev.c

@@ -511,8 +511,9 @@ static void clear_hsave_pa(void *arg)
 	wrmsrq(MSR_VM_HSAVE_PA, 0);
 }
 
-void snp_prepare(void)
+int snp_prepare(void)
 {
+	int ret;
 	u64 val;
 
 	/*
@@ -521,12 +522,20 @@ void snp_prepare(void)
 	 */
 	rdmsrq(MSR_AMD64_SYSCFG, val);
 	if (val & MSR_AMD64_SYSCFG_SNP_EN)
-		return;
+		return 0;
 
 	clear_rmp();
 
 	cpus_read_lock();
 
+	if (!cpumask_equal(cpu_online_mask, cpu_present_mask)) {
+		ret = -EOPNOTSUPP;
+		pr_warn("SNP init failed: not all CPUs online. (%*pbl online <-> %*pbl present masks).\n",
+			cpumask_pr_args(cpu_online_mask),
+			cpumask_pr_args(cpu_present_mask));
+		goto unlock;
+	}
+
 	/*
 	 * MtrrFixDramModEn is not shared between threads on a core,
 	 * therefore it must be set on all CPUs prior to enabling SNP.
@@ -537,7 +546,12 @@ void snp_prepare(void)
 	/* SNP_INIT requires MSR_VM_HSAVE_PA to be cleared on all CPUs. */
 	on_each_cpu(clear_hsave_pa, NULL, 1);
 
+	ret = 0;
+
+unlock:
 	cpus_read_unlock();
+
+	return ret;
 }
 EXPORT_SYMBOL_FOR_MODULES(snp_prepare, "ccp");
 

drivers/crypto/ccp/sev-dev.c

@@ -1374,7 +1374,9 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)
 		return -EOPNOTSUPP;
 	}
 
-	snp_prepare();
+	rc = snp_prepare();
+	if (rc)
+		return rc;
 
 	/*
 	 * Starting in SNP firmware v1.52, the SNP_INIT_EX command takes a list