Merge tag 'x86_sev_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 SEV updates from Borislav Petkov:

 - Change the SEV host code handling of when SNP gets enabled in order
   to allow the machine to claim SNP-related resources only when SNP
   guests are really going to be launched. The user requests this by
   loading the ccp module and thus it controls when SNP initialization
   is done

   So export an API which module code can call and do the necessary SNP
   setup only when really needed

 - Drop an unnecessary write-back and invalidate operation that was
   being performed too early, since the ccp driver already issues its
   own at the correct point in the initialization sequence

 - Drop the hotplug callbacks for enabling SNP on newly onlined CPUs,
   which were both architecturally unsound (the firmware rejects
   initialization if any CPU lacks the required configuration) and buggy
   (the MFDM SYSCFG MSR bit was not being set)

 - Code refactoring and cleanups to accomplish the above

* tag 'x86_sev_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  crypto/ccp: Update HV_FIXED page states to allow freeing of memory
  crypto/ccp: Implement SNP x86 shutdown
  x86/sev, crypto/ccp: Move HSAVE_PA setup to arch/x86/
  x86/sev, crypto/ccp: Move SNP init to ccp driver
  x86/sev: Create snp_shutdown()
  x86/sev: Create snp_prepare()
  x86/sev: Create a function to clear/zero the RMP
  x86/sev: Rename SNP_FEATURES_PRESENT to SNP_FEATURES_IMPL
  x86/virt/sev: Keep the RMP table bookkeeping area mapped
  x86/virt/sev: Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN
  x86/virt/sev: Drop support for SNP hotplug

5 files changed, 135 insertions, 105 deletions

diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index e468476e9e4a..c6512f2ea31e 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -198,11 +198,11 @@ bool sev_es_check_ghcb_fault(unsigned long address)
 #endif
 
 /*
- * SNP_FEATURES_PRESENT is the mask of SNP features that are implemented
+ * SNP_FEATURES_IMPL is the mask of SNP features that are implemented
  * by the guest kernel. As and when a new feature is implemented in the
  * guest kernel, a corresponding bit should be added to the mask.
  */
-#define SNP_FEATURES_PRESENT	(MSR_AMD64_SNP_DEBUG_SWAP |	\
+#define SNP_FEATURES_IMPL	(MSR_AMD64_SNP_DEBUG_SWAP |	\
 				 MSR_AMD64_SNP_SECURE_TSC |	\
 				 SNP_FEATURE_SECURE_AVIC)
 
@@ -211,7 +211,7 @@ u64 snp_get_unsupported_features(u64 status)
 	if (!(status & MSR_AMD64_SEV_SNP_ENABLED))
 		return 0;
 
-	return status & SNP_FEATURES_IMPL_REQ & ~SNP_FEATURES_PRESENT;
+	return status & SNP_FEATURES_IMPL_REQ & ~SNP_FEATURES_IMPL;
 }
 
 void snp_check_features(void)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 0e6c0940100f..09e605c85de4 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -661,6 +661,8 @@ static inline void snp_leak_pages(u64 pfn, unsigned int pages)
 {
 	__snp_leak_pages(pfn, pages, true);
 }
+void snp_prepare(void);
+void snp_shutdown(void);
 #else
 static inline bool snp_probe_rmptable_info(void) { return false; }
 static inline int snp_rmptable_init(void) { return -ENOSYS; }
@@ -677,6 +679,8 @@ 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 void snp_shutdown(void) {}
 #endif
 
 #endif
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index a4f3a364fb65..41f76f15caa1 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -117,6 +117,8 @@ static u64 rmp_segment_mask;
 
 static u64 rmp_cfg;
 
+static void *rmp_bookkeeping __ro_after_init;
+
 /* Mask to apply to a PFN to get the first PFN of a 2MB page */
 #define PFN_PMD_MASK	GENMASK_ULL(63, PMD_SHIFT - PAGE_SHIFT)
 
@@ -130,33 +132,23 @@ static unsigned long snp_nr_leaked_pages;
 #undef pr_fmt
 #define pr_fmt(fmt)	"SEV-SNP: " fmt
 
-static int __mfd_enable(unsigned int cpu)
+static void mfd_reconfigure(void *arg)
 {
-	u64 val;
-
 	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
-		return 0;
-
-	rdmsrq(MSR_AMD64_SYSCFG, val);
-
-	val |= MSR_AMD64_SYSCFG_MFDM;
-
-	wrmsrq(MSR_AMD64_SYSCFG, val);
-
-	return 0;
-}
+		return;
 
-static __init void mfd_enable(void *arg)
-{
-	__mfd_enable(smp_processor_id());
+	if (arg)
+		msr_set_bit(MSR_AMD64_SYSCFG, MSR_AMD64_SYSCFG_MFDM_BIT);
+	else
+		msr_clear_bit(MSR_AMD64_SYSCFG, MSR_AMD64_SYSCFG_MFDM_BIT);
 }
 
-static int __snp_enable(unsigned int cpu)
+static void snp_enable(void *arg)
 {
 	u64 val;
 
 	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
-		return 0;
+		return;
 
 	rdmsrq(MSR_AMD64_SYSCFG, val);
 
@@ -164,13 +156,6 @@ static int __snp_enable(unsigned int cpu)
 	val |= MSR_AMD64_SYSCFG_SNP_VMPL_EN;
 
 	wrmsrq(MSR_AMD64_SYSCFG, val);
-
-	return 0;
-}
-
-static __init void snp_enable(void *arg)
-{
-	__snp_enable(smp_processor_id());
 }
 
 static void __init __snp_fixup_e820_tables(u64 pa)
@@ -260,21 +245,30 @@ void __init snp_fixup_e820_tables(void)
 	}
 }
 
-static bool __init clear_rmptable_bookkeeping(void)
+static void clear_rmp(void)
 {
-	void *bk;
+	unsigned int i;
+	u64 val;
 
-	bk = memremap(probed_rmp_base, RMPTABLE_CPU_BOOKKEEPING_SZ, MEMREMAP_WB);
-	if (!bk) {
-		pr_err("Failed to map RMP bookkeeping area\n");
-		return false;
-	}
+	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
+		return;
 
-	memset(bk, 0, RMPTABLE_CPU_BOOKKEEPING_SZ);
+	/* Clearing the RMP while SNP is enabled will cause an exception */
+	rdmsrq(MSR_AMD64_SYSCFG, val);
+	if (WARN_ON_ONCE(val & MSR_AMD64_SYSCFG_SNP_EN))
+		return;
 
-	memunmap(bk);
+	memset(rmp_bookkeeping, 0, RMPTABLE_CPU_BOOKKEEPING_SZ);
 
-	return true;
+	for (i = 0; i < rst_max_index; i++) {
+		struct rmp_segment_desc *desc;
+
+		desc = rmp_segment_table[i];
+		if (!desc)
+			continue;
+
+		memset(desc->rmp_entry, 0, desc->size);
+	}
 }
 
 static bool __init alloc_rmp_segment_desc(u64 segment_pa, u64 segment_size, u64 pa)
@@ -494,30 +488,32 @@ e_free:
 static bool __init setup_rmptable(void)
 {
 	if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED) {
-		return setup_segmented_rmptable();
+		if (!setup_segmented_rmptable())
+			return false;
 	} else {
-		return setup_contiguous_rmptable();
+		if (!setup_contiguous_rmptable())
+			return false;
 	}
-}
 
-/*
- * Do the necessary preparations which are verified by the firmware as
- * described in the SNP_INIT_EX firmware command description in the SNP
- * firmware ABI spec.
- */
-int __init snp_rmptable_init(void)
-{
-	unsigned int i;
-	u64 val;
+	rmp_bookkeeping = memremap(probed_rmp_base, RMPTABLE_CPU_BOOKKEEPING_SZ, MEMREMAP_WB);
+	if (!rmp_bookkeeping) {
+		pr_err("Failed to map RMP bookkeeping area\n");
+		free_rmp_segment_table();
 
-	if (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP)))
-		return -ENOSYS;
+		return false;
+	}
 
-	if (WARN_ON_ONCE(!amd_iommu_snp_en))
-		return -ENOSYS;
+	return true;
+}
 
-	if (!setup_rmptable())
-		return -ENOSYS;
+static void clear_hsave_pa(void *arg)
+{
+	wrmsrq(MSR_VM_HSAVE_PA, 0);
+}
+
+void snp_prepare(void)
+{
+	u64 val;
 
 	/*
 	 * Check if SEV-SNP is already enabled, this can happen in case of
@@ -525,35 +521,54 @@ int __init snp_rmptable_init(void)
 	 */
 	rdmsrq(MSR_AMD64_SYSCFG, val);
 	if (val & MSR_AMD64_SYSCFG_SNP_EN)
-		goto skip_enable;
+		return;
 
-	/* Zero out the RMP bookkeeping area */
-	if (!clear_rmptable_bookkeeping()) {
-		free_rmp_segment_table();
-		return -ENOSYS;
-	}
+	clear_rmp();
 
-	/* Zero out the RMP entries */
-	for (i = 0; i < rst_max_index; i++) {
-		struct rmp_segment_desc *desc;
+	cpus_read_lock();
 
-		desc = rmp_segment_table[i];
-		if (!desc)
-			continue;
+	/*
+	 * MtrrFixDramModEn is not shared between threads on a core,
+	 * therefore it must be set on all CPUs prior to enabling SNP.
+	 */
+	on_each_cpu(mfd_reconfigure, (void *)1, 1);
+	on_each_cpu(snp_enable, NULL, 1);
 
-		memset(desc->rmp_entry, 0, desc->size);
-	}
+	/* SNP_INIT requires MSR_VM_HSAVE_PA to be cleared on all CPUs. */
+	on_each_cpu(clear_hsave_pa, NULL, 1);
 
-	/* Flush the caches to ensure that data is written before SNP is enabled. */
-	wbinvd_on_all_cpus();
+	cpus_read_unlock();
+}
+EXPORT_SYMBOL_FOR_MODULES(snp_prepare, "ccp");
 
-	/* MtrrFixDramModEn must be enabled on all the CPUs prior to enabling SNP. */
-	on_each_cpu(mfd_enable, NULL, 1);
+void snp_shutdown(void)
+{
+	u64 syscfg;
 
-	on_each_cpu(snp_enable, NULL, 1);
+	rdmsrq(MSR_AMD64_SYSCFG, syscfg);
+	if (syscfg & MSR_AMD64_SYSCFG_SNP_EN)
+		return;
+
+	clear_rmp();
+	on_each_cpu(mfd_reconfigure, NULL, 1);
+}
+EXPORT_SYMBOL_FOR_MODULES(snp_shutdown, "ccp");
 
-skip_enable:
-	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/rmptable_init:online", __snp_enable, NULL);
+/*
+ * Do the necessary preparations which are verified by the firmware as
+ * described in the SNP_INIT_EX firmware command description in the SNP
+ * firmware ABI spec.
+ */
+int __init snp_rmptable_init(void)
+{
+	if (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP)))
+		return -ENOSYS;
+
+	if (WARN_ON_ONCE(!amd_iommu_snp_en))
+		return -ENOSYS;
+
+	if (!setup_rmptable())
+		return -ENOSYS;
 
 	/*
 	 * Setting crash_kexec_post_notifiers to 'true' to ensure that SNP panic
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index aebf4dad545e..939fa8aa155c 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1076,11 +1076,6 @@ static inline int __sev_do_init_locked(int *psp_ret)
 		return __sev_init_locked(psp_ret);
 }
 
-static void snp_set_hsave_pa(void *arg)
-{
-	wrmsrq(MSR_VM_HSAVE_PA, 0);
-}
-
 /* Hypervisor Fixed pages API interface */
 static void snp_hv_fixed_pages_state_update(struct sev_device *sev,
 					    enum snp_hv_fixed_pages_state page_state)
@@ -1224,7 +1219,7 @@ static void snp_add_hv_fixed_pages(struct sev_device *sev, struct sev_data_range
 
 static void snp_leak_hv_fixed_pages(void)
 {
-	struct snp_hv_fixed_pages_entry *entry;
+	struct snp_hv_fixed_pages_entry *entry, *nentry;
 
 	/* List is protected by sev_cmd_mutex */
 	lockdep_assert_held(&sev_cmd_mutex);
@@ -1232,10 +1227,16 @@ static void snp_leak_hv_fixed_pages(void)
 	if (list_empty(&snp_hv_fixed_pages))
 		return;
 
-	list_for_each_entry(entry, &snp_hv_fixed_pages, list)
-		if (entry->page_state == HV_FIXED)
+	list_for_each_entry_safe(entry, nentry, &snp_hv_fixed_pages, list) {
+		if (entry->free && entry->page_state != HV_FIXED)
+			__free_pages(entry->page, entry->order);
+		else
 			__snp_leak_pages(page_to_pfn(entry->page),
 					 1 << entry->order, false);
+
+		list_del(&entry->list);
+		kfree(entry);
+	}
 }
 
 bool sev_is_snp_ciphertext_hiding_supported(void)
@@ -1373,8 +1374,7 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)
 		return -EOPNOTSUPP;
 	}
 
-	/* SNP_INIT requires MSR_VM_HSAVE_PA to be cleared on all CPUs. */
-	on_each_cpu(snp_set_hsave_pa, NULL, 1);
+	snp_prepare();
 
 	/*
 	 * Starting in SNP firmware v1.52, the SNP_INIT_EX command takes a list
@@ -2045,6 +2045,8 @@ static int __sev_snp_shutdown_locked(int *error, bool panic)
 	memset(&data, 0, sizeof(data));
 	data.len = sizeof(data);
 	data.iommu_snp_shutdown = 1;
+	if (sev->snp_feat_info_0.ecx & SNP_X86_SHUTDOWN_SUPPORTED)
+		data.x86_snp_shutdown = 1;
 
 	/*
 	 * If invoked during panic handling, local interrupts are disabled
@@ -2078,23 +2080,29 @@ static int __sev_snp_shutdown_locked(int *error, bool panic)
 		return ret;
 	}
 
-	/*
-	 * SNP_SHUTDOWN_EX with IOMMU_SNP_SHUTDOWN set to 1 disables SNP
-	 * enforcement by the IOMMU and also transitions all pages
-	 * associated with the IOMMU to the Reclaim state.
-	 * Firmware was transitioning the IOMMU pages to Hypervisor state
-	 * before version 1.53. But, accounting for the number of assigned
-	 * 4kB pages in a 2M page was done incorrectly by not transitioning
-	 * to the Reclaim state. This resulted in RMP #PF when later accessing
-	 * the 2M page containing those pages during kexec boot. Hence, the
-	 * firmware now transitions these pages to Reclaim state and hypervisor
-	 * needs to transition these pages to shared state. SNP Firmware
-	 * version 1.53 and above are needed for kexec boot.
-	 */
-	ret = amd_iommu_snp_disable();
-	if (ret) {
-		dev_err(sev->dev, "SNP IOMMU shutdown failed\n");
-		return ret;
+	if (data.x86_snp_shutdown) {
+		if (!panic)
+			snp_shutdown();
+		snp_hv_fixed_pages_state_update(sev, ALLOCATED);
+	} else {
+		/*
+		 * SNP_SHUTDOWN_EX with IOMMU_SNP_SHUTDOWN set to 1 disables SNP
+		 * enforcement by the IOMMU and also transitions all pages
+		 * associated with the IOMMU to the Reclaim state.
+		 * Firmware was transitioning the IOMMU pages to Hypervisor state
+		 * before version 1.53. But, accounting for the number of assigned
+		 * 4kB pages in a 2M page was done incorrectly by not transitioning
+		 * to the Reclaim state. This resulted in RMP #PF when later accessing
+		 * the 2M page containing those pages during kexec boot. Hence, the
+		 * firmware now transitions these pages to Reclaim state and hypervisor
+		 * needs to transition these pages to shared state. SNP Firmware
+		 * version 1.53 and above are needed for kexec boot.
+		 */
+		ret = amd_iommu_snp_disable();
+		if (ret) {
+			dev_err(sev->dev, "SNP IOMMU shutdown failed\n");
+			return ret;
+		}
 	}
 
 	snp_leak_hv_fixed_pages();
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 69ffa4b4d1fa..d5099a2baca5 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -829,12 +829,14 @@ struct sev_data_range_list {
  *
  * @len: length of the command buffer read by the PSP
  * @iommu_snp_shutdown: Disable enforcement of SNP in the IOMMU
+ * @x86_snp_shutdown: Disable SNP on all cores
  * @rsvd1: reserved
  */
 struct sev_data_snp_shutdown_ex {
 	u32 len;
 	u32 iommu_snp_shutdown:1;
-	u32 rsvd1:31;
+	u32 x86_snp_shutdown:1;
+	u32 rsvd1:30;
 } __packed;
 
 /**
@@ -891,6 +893,7 @@ struct snp_feature_info {
 } __packed;
 
 /* Feature bits in ECX */
+#define SNP_X86_SHUTDOWN_SUPPORTED		BIT(1)
 #define SNP_RAPL_DISABLE_SUPPORTED		BIT(2)
 #define SNP_CIPHER_TEXT_HIDING_SUPPORTED	BIT(3)
 #define SNP_AES_256_XTS_POLICY_SUPPORTED	BIT(4)