[RFC PATCH V4 08/17] x86/hyperv: Initialize cpu and memory for sev-snp enlightened guest

[Tianyu Lan <ltykernel@gmail.com>]

From: Tianyu Lan <tiala@microsoft.com>

Read processor amd memory info from specific address which are
populated by Hyper-V. Initialize smp cpu related ops, pvalidate
system memory and add it into e820 table.

Signed-off-by: Tianyu Lan <tiala@microsoft.com>
---
 arch/x86/hyperv/ivm.c           | 78 +++++++++++++++++++++++++++++++++
 arch/x86/include/asm/mshyperv.h | 16 +++++++
 arch/x86/kernel/cpu/mshyperv.c  |  3 ++
 3 files changed, 97 insertions(+)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 368b2731950e..fa4de2761460 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -17,6 +17,11 @@
 #include <asm/mem_encrypt.h>
 #include <asm/mshyperv.h>
 #include <asm/hypervisor.h>
+#include <asm/coco.h>
+#include <asm/io_apic.h>
+#include <asm/sev.h>
+#include <asm/realmode.h>
+#include <asm/e820/api.h>
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 
@@ -57,6 +62,22 @@ union hv_ghcb {
 
 static u16 hv_ghcb_version __ro_after_init;
 
+static u32 processor_count;
+
+static __init void hv_snp_get_smp_config(unsigned int early)
+{
+	if (!early) {
+		while (num_processors < processor_count) {
+			early_per_cpu(x86_cpu_to_apicid, num_processors) = num_processors;
+			early_per_cpu(x86_bios_cpu_apicid, num_processors) = num_processors;
+			physid_set(num_processors, phys_cpu_present_map);
+			set_cpu_possible(num_processors, true);
+			set_cpu_present(num_processors, true);
+			num_processors++;
+		}
+	}
+}
+
 u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
 {
 	union hv_ghcb *hv_ghcb;
@@ -356,6 +377,63 @@ static bool hv_is_private_mmio(u64 addr)
 	return false;
 }
 
+__init void hv_sev_init_mem_and_cpu(void)
+{
+	struct memory_map_entry *entry;
+	struct e820_entry *e820_entry;
+	u64 e820_end;
+	u64 ram_end;
+	u64 page;
+
+	/*
+	 * Hyper-V enlightened snp guest boots kernel
+	 * directly without bootloader and so roms,
+	 * bios regions and reserve resources are not
+	 * available. Set these callback to NULL.
+	 */
+	x86_platform.legacy.reserve_bios_regions = 0;
+	x86_init.resources.probe_roms = x86_init_noop;
+	x86_init.resources.reserve_resources = x86_init_noop;
+	x86_init.mpparse.find_smp_config = x86_init_noop;
+	x86_init.mpparse.get_smp_config = hv_snp_get_smp_config;
+
+	/*
+	 * Hyper-V SEV-SNP enlightened guest doesn't support ioapic
+	 * and legacy APIC page read/write. Switch to hv apic here.
+	 */
+	disable_ioapic_support();
+
+	/* Read processor number and memory layout. */
+	processor_count = *(u32 *)__va(EN_SEV_SNP_PROCESSOR_INFO_ADDR);
+	entry = (struct memory_map_entry *)(__va(EN_SEV_SNP_PROCESSOR_INFO_ADDR)
+			+ sizeof(struct memory_map_entry));
+
+	/*
+	 * E820 table in the memory just describes memory for
+	 * kernel, ACPI table, cmdline, boot params and ramdisk.
+	 * Hyper-V popoulates the rest memory layout in the EN_SEV_
+	 * SNP_PROCESSOR_INFO_ADDR.
+	 */
+	for (; entry->numpages != 0; entry++) {
+		e820_entry = &e820_table->entries[
+				e820_table->nr_entries - 1];
+		e820_end = e820_entry->addr + e820_entry->size;
+		ram_end = (entry->starting_gpn +
+			   entry->numpages) * PAGE_SIZE;
+
+		if (e820_end < entry->starting_gpn * PAGE_SIZE)
+			e820_end = entry->starting_gpn * PAGE_SIZE;
+
+		if (e820_end < ram_end) {
+			pr_info("Hyper-V: add e820 entry [mem %#018Lx-%#018Lx]\n", e820_end, ram_end - 1);
+			e820__range_add(e820_end, ram_end - e820_end,
+					E820_TYPE_RAM);
+			for (page = e820_end; page < ram_end; page += PAGE_SIZE)
+				pvalidate((unsigned long)__va(page), RMP_PG_SIZE_4K, true);
+		}
+	}
+}
+
 void __init hv_vtom_init(void)
 {
 	/*
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 3c15e23162e7..a4a59007b5f2 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -41,6 +41,20 @@ extern bool hv_isolation_type_en_snp(void);
 
 extern union hv_ghcb * __percpu *hv_ghcb_pg;
 
+/*
+ * Hyper-V puts processor and memory layout info
+ * to this address in SEV-SNP enlightened guest.
+ */
+#define EN_SEV_SNP_PROCESSOR_INFO_ADDR 0x802000
+
+struct memory_map_entry {
+	u64 starting_gpn;
+	u64 numpages;
+	u16 type;
+	u16 flags;
+	u32 reserved;
+};
+
 int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
 int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
 int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
@@ -246,12 +260,14 @@ void hv_ghcb_msr_read(u64 msr, u64 *value);
 bool hv_ghcb_negotiate_protocol(void);
 void hv_ghcb_terminate(unsigned int set, unsigned int reason);
 void hv_vtom_init(void);
+void hv_sev_init_mem_and_cpu(void);
 #else
 static inline void hv_ghcb_msr_write(u64 msr, u64 value) {}
 static inline void hv_ghcb_msr_read(u64 msr, u64 *value) {}
 static inline bool hv_ghcb_negotiate_protocol(void) { return false; }
 static inline void hv_ghcb_terminate(unsigned int set, unsigned int reason) {}
 static inline void hv_vtom_init(void) {}
+static inline void hv_sev_init_mem_and_cpu(void) {}
 #endif
 
 extern bool hv_isolation_type_snp(void);
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 2f2dcb2370b6..71820bbf9e90 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -529,6 +529,9 @@ static void __init ms_hyperv_init_platform(void)
 	if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT))
 		mark_tsc_unstable("running on Hyper-V");
 
+	if (hv_isolation_type_en_snp())
+		hv_sev_init_mem_and_cpu();
+
 	hardlockup_detector_disable();
 }
 
-- 
2.25.1