From: Tom Lendacky <thomas.lendacky@amd.com>
Subject: [PATCH v6 23/34] x86,
 realmode: Decrypt trampoline area if memory encryption is active
To: linux-arch@vger.kernel.org, linux-efi@vger.kernel.org,
        kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org,
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Cc: Rik van Riel <riel@redhat.com>,
        Radim =?utf-8?b?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Toshimitsu Kani <toshi.kani@hpe.com>, Arnd Bergmann <arnd@arndb.de>,
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        Matt Fleming <matt@codeblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@redhat.com>, Joerg Roedel <joro@8bytes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
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        Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
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        Andrey Ryabinin <aryabinin@virtuozzo.com>,
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        Dmitry Vyukov <dvyukov@google.com>
Date: Wed, 07 Jun 2017 14:17:09 -0500
Message-ID: <20170607191709.28645.69034.stgit@tlendack-t1.amdoffice.net>
In-Reply-To: <20170607191309.28645.15241.stgit@tlendack-t1.amdoffice.net>
References: <20170607191309.28645.15241.stgit@tlendack-t1.amdoffice.net>
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When Secure Memory Encryption is enabled, the trampoline area must not
be encrypted. A CPU running in real mode will not be able to decrypt
memory that has been encrypted because it will not be able to use addresses
with the memory encryption mask.

A recent change that added a new system_state value exposed a warning
issued by early_ioreamp() when the system_state was not SYSTEM_BOOTING.
At the stage where the trampoline area is decrypted, the system_state is
now SYSTEM_SCHEDULING. The check was changed to issue a warning if the
system_state is greater than or equal to SYSTEM_RUNNING.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/realmode/init.c |   11 +++++++++++
 mm/early_ioremap.c       |    2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index a163a90..195ba29 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -6,6 +6,7 @@
 #include <asm/pgtable.h>
 #include <asm/realmode.h>
 #include <asm/tlbflush.h>
+#include <asm/mem_encrypt.h>
 
 struct real_mode_header *real_mode_header;
 u32 *trampoline_cr4_features;
@@ -130,6 +131,16 @@ static void __init set_real_mode_permissions(void)
 	unsigned long text_start =
 		(unsigned long) __va(real_mode_header->text_start);
 
+	/*
+	 * If SME is active, the trampoline area will need to be in
+	 * decrypted memory in order to bring up other processors
+	 * successfully.
+	 */
+	if (sme_active()) {
+		sme_early_decrypt(__pa(base), size);
+		set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
+	}
+
 	set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
 	set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
 	set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c
index b1dd4a9..01d13ae 100644
--- a/mm/early_ioremap.c
+++ b/mm/early_ioremap.c
@@ -110,7 +110,7 @@ static int __init check_early_ioremap_leak(void)
 	enum fixed_addresses idx;
 	int i, slot;
 
-	WARN_ON(system_state != SYSTEM_BOOTING);
+	WARN_ON(system_state >= SYSTEM_RUNNING);
 
 	slot = -1;
 	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {