Merge tag 'hyperv-next-signed-20211102' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv updates from Wei Liu:

 - Initial patch set for Hyper-V isolation VM support (Tianyu Lan)

 - Fix a warning on preemption (Vitaly Kuznetsov)

 - A bunch of misc cleanup patches

* tag 'hyperv-next-signed-20211102' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  x86/hyperv: Protect set_hv_tscchange_cb() against getting preempted
  Drivers: hv : vmbus: Adding NULL pointer check
  x86/hyperv: Remove duplicate include
  x86/hyperv: Remove duplicated include in hv_init
  Drivers: hv: vmbus: Remove unused code to check for subchannels
  Drivers: hv: vmbus: Initialize VMbus ring buffer for Isolation VM
  Drivers: hv: vmbus: Add SNP support for VMbus channel initiate message
  x86/hyperv: Add ghcb hvcall support for SNP VM
  x86/hyperv: Add Write/Read MSR registers via ghcb page
  Drivers: hv: vmbus: Mark vmbus ring buffer visible to host in Isolation VM
  x86/hyperv: Add new hvcall guest address host visibility support
  x86/hyperv: Initialize shared memory boundary in the Isolation VM.
  x86/hyperv: Initialize GHCB page in Isolation VM

Author: torvalds

arch/x86/hyperv/Makefile

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
-obj-y			:= hv_init.o mmu.o nested.o irqdomain.o
+obj-y			:= hv_init.o mmu.o nested.o irqdomain.o ivm.o
 obj-$(CONFIG_X86_64)	+= hv_apic.o hv_proc.o
 
 ifdef CONFIG_X86_64

arch/x86/hyperv/hv_init.c

@@ -36,12 +36,42 @@ EXPORT_SYMBOL_GPL(hv_current_partition_id);
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
 
+union hv_ghcb __percpu **hv_ghcb_pg;
+
 /* Storage to save the hypercall page temporarily for hibernation */
 static void *hv_hypercall_pg_saved;
 
 struct hv_vp_assist_page **hv_vp_assist_page;
 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
 
+static int hyperv_init_ghcb(void)
+{
+	u64 ghcb_gpa;
+	void *ghcb_va;
+	void **ghcb_base;
+
+	if (!hv_isolation_type_snp())
+		return 0;
+
+	if (!hv_ghcb_pg)
+		return -EINVAL;
+
+	/*
+	 * GHCB page is allocated by paravisor. The address
+	 * returned by MSR_AMD64_SEV_ES_GHCB is above shared
+	 * memory boundary and map it here.
+	 */
+	rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
+	ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+	if (!ghcb_va)
+		return -ENOMEM;
+
+	ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
+	*ghcb_base = ghcb_va;
+
+	return 0;
+}
+
 static int hv_cpu_init(unsigned int cpu)
 {
 	union hv_vp_assist_msr_contents msr = { 0 };
@@ -85,7 +115,7 @@ static int hv_cpu_init(unsigned int cpu)
 		}
 	}
 
-	return 0;
+	return hyperv_init_ghcb();
 }
 
 static void (*hv_reenlightenment_cb)(void);
@@ -139,7 +169,6 @@ void set_hv_tscchange_cb(void (*cb)(void))
 	struct hv_reenlightenment_control re_ctrl = {
 		.vector = HYPERV_REENLIGHTENMENT_VECTOR,
 		.enabled = 1,
-		.target_vp = hv_vp_index[smp_processor_id()]
 	};
 	struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 
@@ -153,8 +182,12 @@ void set_hv_tscchange_cb(void (*cb)(void))
 	/* Make sure callback is registered before we write to MSRs */
 	wmb();
 
+	re_ctrl.target_vp = hv_vp_index[get_cpu()];
+
 	wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 	wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
+
+	put_cpu();
 }
 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 
@@ -177,6 +210,14 @@ static int hv_cpu_die(unsigned int cpu)
 {
 	struct hv_reenlightenment_control re_ctrl;
 	unsigned int new_cpu;
+	void **ghcb_va;
+
+	if (hv_ghcb_pg) {
+		ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
+		if (*ghcb_va)
+			memunmap(*ghcb_va);
+		*ghcb_va = NULL;
+	}
 
 	hv_common_cpu_die(cpu);
 
@@ -366,10 +407,16 @@ void __init hyperv_init(void)
 		goto common_free;
 	}
 
+	if (hv_isolation_type_snp()) {
+		hv_ghcb_pg = alloc_percpu(union hv_ghcb *);
+		if (!hv_ghcb_pg)
+			goto free_vp_assist_page;
+	}
+
 	cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 				  hv_cpu_init, hv_cpu_die);
 	if (cpuhp < 0)
-		goto free_vp_assist_page;
+		goto free_ghcb_page;
 
 	/*
 	 * Setup the hypercall page and enable hypercalls.
@@ -379,14 +426,15 @@ void __init hyperv_init(void)
 	guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 
+	/* Hyper-V requires to write guest os id via ghcb in SNP IVM. */
+	hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);
+
 	hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
 			VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
 			VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
 			__builtin_return_address(0));
-	if (hv_hypercall_pg == NULL) {
-		wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
-		goto remove_cpuhp_state;
-	}
+	if (hv_hypercall_pg == NULL)
+		goto clean_guest_os_id;
 
 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 	hypercall_msr.enable = 1;
@@ -456,8 +504,12 @@ void __init hyperv_init(void)
 	hv_query_ext_cap(0);
 	return;
 
-remove_cpuhp_state:
+clean_guest_os_id:
+	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
+	hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
 	cpuhp_remove_state(cpuhp);
+free_ghcb_page:
+	free_percpu(hv_ghcb_pg);
 free_vp_assist_page:
 	kfree(hv_vp_assist_page);
 	hv_vp_assist_page = NULL;
@@ -476,6 +528,7 @@ void hyperv_cleanup(void)
 
 	/* Reset our OS id */
 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
+	hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
 
 	/*
 	 * Reset hypercall page reference before reset the page,
@@ -546,16 +599,3 @@ bool hv_is_hyperv_initialized(void)
 	return hypercall_msr.enable;
 }
 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
-
-enum hv_isolation_type hv_get_isolation_type(void)
-{
-	if (!(ms_hyperv.priv_high & HV_ISOLATION))
-		return HV_ISOLATION_TYPE_NONE;
-	return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
-}
-EXPORT_SYMBOL_GPL(hv_get_isolation_type);
-
-bool hv_is_isolation_supported(void)
-{
-	return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
-}