[PATCH v2 6/6] Drivers: hv: vmbus: Support TDX guests

[Dexuan Cui <decui@microsoft.com>]

Add Hyper-V specific code so that a TDX guest can run on Hyper-V:
  No need to use hv_vp_assist_page.
  Don't use the unsafe Hyper-V TSC page.
  Don't try to use HV_REGISTER_CRASH_CTL.
  Share SynIC Event/Message pages and VMBus Monitor pages with the host.
  Use pgprot_decrypted(PAGE_KERNEL_NOENC))in hv_ringbuffer_init().

Signed-off-by: Dexuan Cui <decui@microsoft.com>

Changes in v2:
  Used a new function hv_set_memory_enc_dec_needed() in
    __set_memory_enc_pgtable().
  Added the missing set_memory_encrypted() in hv_synic_free().
  
---

 arch/x86/hyperv/hv_init.c      | 19 ++++++++---
 arch/x86/hyperv/ivm.c          |  5 +++
 arch/x86/kernel/cpu/mshyperv.c | 17 +++++++++-
 arch/x86/mm/pat/set_memory.c   |  2 +-
 drivers/hv/connection.c        |  4 ++-
 drivers/hv/hv.c                | 60 +++++++++++++++++++++++++++++++++-
 drivers/hv/hv_common.c         |  6 ++++
 drivers/hv/ring_buffer.c       |  2 +-
 include/asm-generic/mshyperv.h |  2 ++
 9 files changed, 108 insertions(+), 9 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index c0ba53ad8b8e..8d7b63346194 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -77,7 +77,7 @@ static int hyperv_init_ghcb(void)
 static int hv_cpu_init(unsigned int cpu)
 {
 	union hv_vp_assist_msr_contents msr = { 0 };
-	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[cpu];
+	struct hv_vp_assist_page **hvp;
 	int ret;
 
 	ret = hv_common_cpu_init(cpu);
@@ -87,6 +87,7 @@ static int hv_cpu_init(unsigned int cpu)
 	if (!hv_vp_assist_page)
 		return 0;
 
+	hvp = &hv_vp_assist_page[cpu];
 	if (hv_root_partition) {
 		/*
 		 * For root partition we get the hypervisor provided VP assist
@@ -396,11 +397,21 @@ void __init hyperv_init(void)
 	if (hv_common_init())
 		return;
 
-	hv_vp_assist_page = kcalloc(num_possible_cpus(),
-				    sizeof(*hv_vp_assist_page), GFP_KERNEL);
+	/*
+	 * The VP assist page is useless to a TDX guest: the only use we
+	 * would have for it is lazy EOI, which can not be used with TDX.
+	 */
+	if (hv_isolation_type_tdx())
+		hv_vp_assist_page = NULL;
+	else
+		hv_vp_assist_page = kcalloc(num_possible_cpus(),
+					    sizeof(*hv_vp_assist_page),
+					    GFP_KERNEL);
 	if (!hv_vp_assist_page) {
 		ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
-		goto common_free;
+
+		if (!hv_isolation_type_tdx())
+			goto common_free;
 	}
 
 	if (hv_isolation_type_snp()) {
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 07e4253b5809..4398042f10d5 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -258,6 +258,11 @@ bool hv_is_isolation_supported(void)
 	return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
 }
 
+bool hv_set_memory_enc_dec_needed(void)
+{
+	return hv_is_isolation_supported() && !hv_isolation_type_tdx();
+}
+
 DEFINE_STATIC_KEY_FALSE(isolation_type_snp);
 
 /*
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 941372449ff2..24569da3c1f8 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -345,8 +345,23 @@ static void __init ms_hyperv_init_platform(void)
 		}
 
 		if (IS_ENABLED(CONFIG_INTEL_TDX_GUEST) &&
-		    hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX)
+		    hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX) {
 			static_branch_enable(&isolation_type_tdx);
+
+			/*
+			 * The GPAs of SynIC Event/Message pages and VMBus
+			 * Moniter pages need to be added by this offset.
+			 */
+			ms_hyperv.shared_gpa_boundary = cc_mkdec(0);
+
+			/* Don't use the unsafe Hyper-V TSC page */
+			ms_hyperv.features &=
+				~HV_MSR_REFERENCE_TSC_AVAILABLE;
+
+			/* HV_REGISTER_CRASH_CTL is unsupported */
+			ms_hyperv.misc_features &=
+				 ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
+		}
 	}
 
 	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 2e5a045731de..5892196f8ade 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -2120,7 +2120,7 @@ static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc)
 
 static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
 {
-	if (hv_is_isolation_supported())
+	if (hv_set_memory_enc_dec_needed())
 		return hv_set_mem_host_visibility(addr, numpages, !enc);
 
 	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 9dc27e5d367a..1ecc3c29e3f7 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -250,12 +250,14 @@ int vmbus_connect(void)
 		 * Isolation VM with AMD SNP needs to access monitor page via
 		 * address space above shared gpa boundary.
 		 */
-		if (hv_isolation_type_snp()) {
+		if (hv_isolation_type_snp() || hv_isolation_type_tdx()) {
 			vmbus_connection.monitor_pages_pa[0] +=
 				ms_hyperv.shared_gpa_boundary;
 			vmbus_connection.monitor_pages_pa[1] +=
 				ms_hyperv.shared_gpa_boundary;
+		}
 
+		if (hv_isolation_type_snp()) {
 			vmbus_connection.monitor_pages[0]
 				= memremap(vmbus_connection.monitor_pages_pa[0],
 					   HV_HYP_PAGE_SIZE,
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 4d6480d57546..78aca415985c 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -18,6 +18,7 @@
 #include <linux/clockchips.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
+#include <linux/set_memory.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 #include "hyperv_vmbus.h"
@@ -119,6 +120,7 @@ int hv_synic_alloc(void)
 {
 	int cpu;
 	struct hv_per_cpu_context *hv_cpu;
+	int ret = -ENOMEM;
 
 	/*
 	 * First, zero all per-cpu memory areas so hv_synic_free() can
@@ -168,6 +170,30 @@ int hv_synic_alloc(void)
 			pr_err("Unable to allocate post msg page\n");
 			goto err;
 		}
+
+
+		if (hv_isolation_type_tdx()) {
+			ret = set_memory_decrypted(
+				(unsigned long)hv_cpu->synic_message_page, 1);
+			if (ret) {
+				pr_err("Failed to decrypt SYNIC msg page\n");
+				goto err;
+			}
+
+			ret = set_memory_decrypted(
+				(unsigned long)hv_cpu->synic_event_page, 1);
+			if (ret) {
+				pr_err("Failed to decrypt SYNIC event page\n");
+				goto err;
+			}
+
+			ret = set_memory_decrypted(
+				(unsigned long)hv_cpu->post_msg_page, 1);
+			if (ret) {
+				pr_err("Failed to decrypt post msg page\n");
+				goto err;
+			}
+		}
 	}
 
 	return 0;
@@ -176,18 +202,42 @@ int hv_synic_alloc(void)
 	 * Any memory allocations that succeeded will be freed when
 	 * the caller cleans up by calling hv_synic_free()
 	 */
-	return -ENOMEM;
+	return ret;
 }
 
 
 void hv_synic_free(void)
 {
 	int cpu;
+	int ret;
 
 	for_each_present_cpu(cpu) {
 		struct hv_per_cpu_context *hv_cpu
 			= per_cpu_ptr(hv_context.cpu_context, cpu);
 
+		if (hv_isolation_type_tdx()) {
+			ret = set_memory_encrypted(
+				(unsigned long)hv_cpu->synic_message_page, 1);
+			if (ret) {
+				pr_err("Failed to encrypt SYNIC msg page\n");
+				continue;
+			}
+
+			ret = set_memory_encrypted(
+				(unsigned long)hv_cpu->synic_event_page, 1);
+			if (ret) {
+				pr_err("Failed to encrypt SYNIC event page\n");
+				continue;
+			}
+
+			ret = set_memory_encrypted(
+				(unsigned long)hv_cpu->post_msg_page, 1);
+			if (ret) {
+				pr_err("Failed to encrypt post msg page\n");
+				continue;
+			}
+		}
+
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
 		free_page((unsigned long)hv_cpu->post_msg_page);
@@ -225,6 +275,10 @@ void hv_synic_enable_regs(unsigned int cpu)
 	} else {
 		simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
 			>> HV_HYP_PAGE_SHIFT;
+
+		if (hv_isolation_type_tdx())
+			simp.base_simp_gpa |= ms_hyperv.shared_gpa_boundary
+				>> HV_HYP_PAGE_SHIFT;
 	}
 
 	hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
@@ -243,6 +297,10 @@ void hv_synic_enable_regs(unsigned int cpu)
 	} else {
 		siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
 			>> HV_HYP_PAGE_SHIFT;
+
+		if (hv_isolation_type_tdx())
+			siefp.base_siefp_gpa |= ms_hyperv.shared_gpa_boundary
+				>> HV_HYP_PAGE_SHIFT;
 	}
 
 	hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index a9a03ab04b97..192dcf295dfc 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -262,6 +262,12 @@ bool __weak hv_is_isolation_supported(void)
 }
 EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
 
+bool __weak hv_set_memory_enc_dec_needed(void)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(hv_set_memory_enc_dec_needed);
+
 bool __weak hv_isolation_type_snp(void)
 {
 	return false;
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index c6692fd5ab15..a51da82316ce 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -233,7 +233,7 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
 
 		ring_info->ring_buffer = (struct hv_ring_buffer *)
 			vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
-				PAGE_KERNEL);
+				pgprot_decrypted(PAGE_KERNEL_NOENC));
 
 		kfree(pages_wraparound);
 		if (!ring_info->ring_buffer)
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index bfb9eb9d7215..b7b1b18c9854 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -262,6 +262,7 @@ bool hv_is_hyperv_initialized(void);
 bool hv_is_hibernation_supported(void);
 enum hv_isolation_type hv_get_isolation_type(void);
 bool hv_is_isolation_supported(void);
+bool hv_set_memory_enc_dec_needed(void);
 bool hv_isolation_type_snp(void);
 u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size);
 void hyperv_cleanup(void);
@@ -274,6 +275,7 @@ static inline bool hv_is_hyperv_initialized(void) { return false; }
 static inline bool hv_is_hibernation_supported(void) { return false; }
 static inline void hyperv_cleanup(void) {}
 static inline bool hv_is_isolation_supported(void) { return false; }
+static inline bool hv_set_memory_enc_dec_needed(void) { return false; }
 static inline enum hv_isolation_type hv_get_isolation_type(void)
 {
 	return HV_ISOLATION_TYPE_NONE;
-- 
2.25.1