linux-kernel - Re: [PATCH v6 14/34] x86/mm: Insure that boot memory areas are mapped properly

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Message-ID: <20170610160119.bnx5ir5dj3i27igx@pd.tnic>
Date:   Sat, 10 Jun 2017 18:01:19 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        iommu@...ts.linux-foundation.org, Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v6 14/34] x86/mm: Insure that boot memory areas are
 mapped properly

On Wed, Jun 07, 2017 at 02:15:39PM -0500, Tom Lendacky wrote:
> The boot data and command line data are present in memory in a decrypted
> state and are copied early in the boot process.  The early page fault
> support will map these areas as encrypted, so before attempting to copy
> them, add decrypted mappings so the data is accessed properly when copied.
> 
> For the initrd, encrypt this data in place. Since the future mapping of the
> initrd area will be mapped as encrypted the data will be accessed properly.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  arch/x86/include/asm/mem_encrypt.h |   11 +++++
>  arch/x86/include/asm/pgtable.h     |    3 +
>  arch/x86/kernel/head64.c           |   30 ++++++++++++--
>  arch/x86/kernel/setup.c            |    9 ++++
>  arch/x86/mm/mem_encrypt.c          |   77 ++++++++++++++++++++++++++++++++++++
>  5 files changed, 126 insertions(+), 4 deletions(-)

Some cleanups ontop in case you get to send v7:

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 61a704945294..5959a42dd4d5 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -45,13 +45,8 @@ static inline void __init sme_early_decrypt(resource_size_t paddr,
 {
 }
 
-static inline void __init sme_map_bootdata(char *real_mode_data)
-{
-}
-
-static inline void __init sme_unmap_bootdata(char *real_mode_data)
-{
-}
+static inline void __init sme_map_bootdata(char *real_mode_data)	{ }
+static inline void __init sme_unmap_bootdata(char *real_mode_data)	{ }
 
 static inline void __init sme_early_init(void)
 {
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 2321f05045e5..32ebbe0ab04d 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -132,6 +132,10 @@ static void __init __sme_map_unmap_bootdata(char *real_mode_data, bool map)
 	struct boot_params *boot_data;
 	unsigned long cmdline_paddr;
 
+	/* If SME is not active, the bootdata is in the correct state */
+	if (!sme_active())
+		return;
+
 	__sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), map);
 	boot_data = (struct boot_params *)real_mode_data;
 
@@ -142,40 +146,22 @@ static void __init __sme_map_unmap_bootdata(char *real_mode_data, bool map)
 	cmdline_paddr = boot_data->hdr.cmd_line_ptr |
 			((u64)boot_data->ext_cmd_line_ptr << 32);
 
-	if (cmdline_paddr)
-		__sme_early_map_unmap_mem(__va(cmdline_paddr),
-					  COMMAND_LINE_SIZE, map);
+	if (!cmdline_paddr)
+		return;
+
+	__sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, map);
+
+	sme_early_pgtable_flush();
 }
 
 void __init sme_unmap_bootdata(char *real_mode_data)
 {
-	/* If SME is not active, the bootdata is in the correct state */
-	if (!sme_active())
-		return;
-
-	/*
-	 * The bootdata and command line aren't needed anymore so clear
-	 * any mapping of them.
-	 */
 	__sme_map_unmap_bootdata(real_mode_data, false);
-
-	sme_early_pgtable_flush();
 }
 
 void __init sme_map_bootdata(char *real_mode_data)
 {
-	/* If SME is not active, the bootdata is in the correct state */
-	if (!sme_active())
-		return;
-
-	/*
-	 * The bootdata and command line will not be encrypted, so they
-	 * need to be mapped as decrypted memory so they can be copied
-	 * properly.
-	 */
 	__sme_map_unmap_bootdata(real_mode_data, true);
-
-	sme_early_pgtable_flush();
 }
 
 void __init sme_early_init(void)

-- 
Regards/Gruss,
    Boris.

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