[v3,43/75] x86/sev-es: Setup per-cpu GHCBs for the runtime handler

Commit Message

Joerg Roedel April 28, 2020, 3:16 p.m. UTC

From: Tom Lendacky <[e-mail]>

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

Signed-off-by: Tom Lendacky <[e-mail]>
Signed-off-by: Joerg Roedel <[e-mail]>
---
 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(-)

Comments

Borislav Petkov May 22, 2020, 8:33 a.m. UTC | #1

On Tue, Apr 28, 2020 at 05:16:53PM +0200, Joerg Roedel wrote:
> @@ -198,6 +210,48 @@ static bool __init sev_es_setup_ghcb(void)
>  	return true;
>  }
>  
> +static void __init sev_es_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 sev_es_init_ghcb(int cpu)

Since those are static functions, I'd drop the "sev_es_" prefix from the
name for better readability. Because otherwise the whole file is a sea
of "sev_es_"-prefixed identifiers which you need to read until the end
to know what they are.

> +{
> +	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");

			"Error mapping ..."

> +
> +	memset(&data->ghcb_page, 0, sizeof(data->ghcb_page));
> +}

Patch

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 6f61bb93366a..af3e58aa1603 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -48,6 +48,7 @@  int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size);
 void __init mem_encrypt_init(void);
 void __init mem_encrypt_free_decrypted_mem(void);
 
+void __init sev_es_init_vc_handling(void);
 bool sme_active(void);
 bool sev_active(void);
 bool sev_es_active(void);
@@ -71,6 +72,7 @@  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 9de5bb23cb0a..a43d80d5e50e 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/trap_defs.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_vc_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 sev_es_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 sev_es_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) {
+		sev_es_alloc_runtime_data(cpu);
+		sev_es_init_ghcb(cpu);
+	}
+}
+
 static void __init vc_early_vc_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 d54cffdc7cac..411928c38cd7 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -965,6 +965,9 @@  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();
 
 	/*