linux-kernel - [PATCH 5.9 088/255] x86/boot/compressed/64: Introduce sev

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Message-Id: <20201117122143.241789632@linuxfoundation.org>
Date:   Tue, 17 Nov 2020 14:03:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
        Borislav Petkov <bp@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 088/255] x86/boot/compressed/64: Introduce sev_status

From: Joerg Roedel <jroedel@...e.de>

[ Upstream commit 3ad84246a4097010f3ae3d6944120c0be00e9e7a ]

Introduce sev_status and initialize it together with sme_me_mask to have
an indicator which SEV features are enabled.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
Link: https://lkml.kernel.org/r/20201028164659.27002-2-joro@8bytes.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/boot/compressed/mem_encrypt.S | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S
index dd07e7b41b115..3092ae173f94e 100644
--- a/arch/x86/boot/compressed/mem_encrypt.S
+++ b/arch/x86/boot/compressed/mem_encrypt.S
@@ -81,6 +81,19 @@ SYM_FUNC_START(set_sev_encryption_mask)
 
 	bts	%rax, sme_me_mask(%rip)	/* Create the encryption mask */
 
+	/*
+	 * Read MSR_AMD64_SEV again and store it to sev_status. Can't do this in
+	 * get_sev_encryption_bit() because this function is 32-bit code and
+	 * shared between 64-bit and 32-bit boot path.
+	 */
+	movl	$MSR_AMD64_SEV, %ecx	/* Read the SEV MSR */
+	rdmsr
+
+	/* Store MSR value in sev_status */
+	shlq	$32, %rdx
+	orq	%rdx, %rax
+	movq	%rax, sev_status(%rip)
+
 .Lno_sev_mask:
 	movq	%rbp, %rsp		/* Restore original stack pointer */
 
@@ -96,5 +109,6 @@ SYM_FUNC_END(set_sev_encryption_mask)
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 	.balign	8
-SYM_DATA(sme_me_mask, .quad 0)
+SYM_DATA(sme_me_mask,		.quad 0)
+SYM_DATA(sev_status,		.quad 0)
 #endif
-- 
2.27.0