linux-kernel - [PATCH 40/70] x86/sev-es: Setup per-cpu GHCBs for the runtime handler

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Message-Id: <20200319091407.1481-41-joro@8bytes.org>
Date:   Thu, 19 Mar 2020 10:13:37 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     x86@...nel.org
Cc:     hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Joerg Roedel <joro@...tes.org>, Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 40/70] x86/sev-es: Setup per-cpu GHCBs for the runtime handler

From: Tom Lendacky <thomas.lendacky@....com>

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

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 arch/x86/include/asm/mem_encrypt.h |  2 ++
 arch/x86/kernel/sev-es.c           | 28 +++++++++++++++++++++++++++-
 arch/x86/kernel/traps.c            |  3 +++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 6f61bb93366a..8b69b389688f 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_ghcbs(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_ghcbs(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 c17980e8db78..4bf5286310a0 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -8,8 +8,11 @@
  */
 
 #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/set_memory.h>
+#include <linux/kernel.h>
 #include <linux/mm.h>
 
 #include <asm/trap_defs.h>
@@ -29,6 +32,9 @@ struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE);
  */
 struct ghcb __initdata *boot_ghcb;
 
+/* Runtime GHCB pointers */
+static struct ghcb __percpu *ghcb_page;
+
 /* Needed in vc_early_vc_forward_exception */
 extern void early_exception(struct pt_regs *regs, int trapnr);
 
@@ -197,6 +203,26 @@ static bool __init sev_es_setup_ghcb(void)
 	return true;
 }
 
+void sev_es_init_ghcbs(void)
+{
+	int cpu;
+
+	if (!sev_es_active())
+		return;
+
+	/* Allocate GHCB pages */
+	ghcb_page = __alloc_percpu(sizeof(struct ghcb), PAGE_SIZE);
+
+	/* Initialize per-cpu GHCB pages */
+	for_each_possible_cpu(cpu) {
+		struct ghcb *ghcb = (struct ghcb *)per_cpu_ptr(ghcb_page, cpu);
+
+		set_memory_decrypted((unsigned long)ghcb,
+				     sizeof(*ghcb) >> PAGE_SHIFT);
+		memset(ghcb, 0, sizeof(*ghcb));
+	}
+}
+
 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 6ef00eb6fbb9..09bebda9b053 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -918,6 +918,9 @@ 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_ghcbs();
+
 	idt_setup_traps();
 
 	/*
-- 
2.17.1