[PATCH v7 41/72] x86/sev-es: Setup per-cpu GHCBs for the runtime handler

Joerg Roedel
2020-09-07T13:15:42Z

From: Tom Lendacky <thomas.lendacky at amd.com>

The runtime handler needs a GHCB per CPU. Set them up and map them
unencrypted.

Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/include/asm/mem_encrypt.h |  2 ++
 arch/x86/kernel/sev-es.c           | 56 +++++++++++++++++++++++++++++-
 arch/x86/kernel/traps.c            |  3 ++
 3 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/mem_encrypt.h
b/arch/x86/include/asm/mem_encrypt.h
index 4e72b73a9cb5..c9f5df0a1c10 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -49,6 +49,7 @@ void __init mem_encrypt_free_decrypted_mem(void);
 /* Architecture __weak replacement functions */
 void __init mem_encrypt_init(void);

+void __init sev_es_init_vc_handling(void);
 bool sme_active(void);
 bool sev_active(void);
 bool sev_es_active(void);
@@ -72,6 +73,7 @@ static inline void __init sme_early_init(void) { }
 static inline void __init sme_encrypt_kernel(struct boot_params *bp) { }
 static inline void __init sme_enable(struct boot_params *bp) { }

+static inline void sev_es_init_vc_handling(void) { }
 static inline bool sme_active(void) { return false; }
 static inline bool sev_active(void) { return false; }
 static inline bool sev_es_active(void) { return false; }
diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index bb3e702a71eb..0f28bb1c0022 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -8,8 +8,13 @@
  */

 #include <linux/sched/debug.h>	/* For show_regs() */
-#include <linux/kernel.h>
+#include <linux/percpu-defs.h>
+#include <linux/mem_encrypt.h>
 #include <linux/printk.h>
+#include <linux/mm_types.h>
+#include <linux/set_memory.h>
+#include <linux/memblock.h>
+#include <linux/kernel.h>
 #include <linux/mm.h>

 #include <asm/sev-es.h>
@@ -29,6 +34,13 @@ static struct ghcb boot_ghcb_page __bss_decrypted
__aligned(PAGE_SIZE);
  */
 static struct ghcb __initdata *boot_ghcb;

+/* #VC handler runtime per-cpu data */
+struct sev_es_runtime_data {
+	struct ghcb ghcb_page;
+};
+
+static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data);
+
 /* Needed in vc_early_forward_exception */
 void do_early_exception(struct pt_regs *regs, int trapnr);

@@ -198,6 +210,48 @@ static bool __init sev_es_setup_ghcb(void)
 	return true;
 }

+static void __init alloc_runtime_data(int cpu)
+{
+	struct sev_es_runtime_data *data;
+
+	data = memblock_alloc(sizeof(*data), PAGE_SIZE);
+	if (!data)
+		panic("Can't allocate SEV-ES runtime data");
+
+	per_cpu(runtime_data, cpu) = data;
+}
+
+static void __init init_ghcb(int cpu)
+{
+	struct sev_es_runtime_data *data;
+	int err;
+
+	data = per_cpu(runtime_data, cpu);
+
+	err = early_set_memory_decrypted((unsigned long)&data->ghcb_page,
+					 sizeof(data->ghcb_page));
+	if (err)
+		panic("Can not map GHCBs unencrypted");
+
+	memset(&data->ghcb_page, 0, sizeof(data->ghcb_page));
+}
+
+void __init sev_es_init_vc_handling(void)
+{
+	int cpu;
+
+	BUILD_BUG_ON((offsetof(struct sev_es_runtime_data, ghcb_page) % PAGE_SIZE) !=
0);
+
+	if (!sev_es_active())
+		return;
+
+	/* Initialize per-cpu GHCB pages */
+	for_each_possible_cpu(cpu) {
+		alloc_runtime_data(cpu);
+		init_ghcb(cpu);
+	}
+}
+
 static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt)
 {
 	int trapnr = ctxt->fi.vector;
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index df9c6554f83e..e121e7c5f831 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -1082,6 +1082,9 @@ void __init trap_init(void)
 	/* Init cpu_entry_area before IST entries are set up */
 	setup_cpu_entry_areas();

+	/* Init GHCB memory pages when running as an SEV-ES guest */
+	sev_es_init_vc_handling();
+
 	idt_setup_traps();

 	/*
--
2.28.0