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Subject[PATCH v5 43/75] x86/sev-es: Setup per-cpu GHCBs for the runtime handler
Date
From: Tom Lendacky <thomas.lendacky@amd.com>

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

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Joerg Roedel <jroedel@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..734afaee378d 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 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_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 8493f55e1167..bf850127c442 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -1078,6 +1078,9 @@ 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();

/*
--
2.27.0
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