From: Tom Lendacky <thomas.lendacky@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-arch@vger.kernel.org, linux-efi@vger.kernel.org,
kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
"Rik van Riel" <riel@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Toshimitsu Kani" <toshi.kani@hpe.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Jonathan Corbet" <corbet@lwn.net>,
"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>,
"Brijesh Singh" <brijesh.singh@amd.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Alexander Potapenko" <glider@google.com>,
"Andy Lutomirski" <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Andrey Ryabinin" <aryabinin@virtuozzo.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Larry Woodman" <lwoodman@redhat.com>,
"Dmitry Vyukov" <dvyukov@google.com>
Subject: Re: [RFC PATCH v4 28/28] x86: Add support to make use of Secure Memory Encryption
Date: Tue, 7 Mar 2017 10:05:00 -0600 [thread overview]
Message-ID: <7e6c308f-3caf-5531-3cb2-9b6986f4288e@amd.com> (raw)
In-Reply-To: <20170301184055.gl3iic3gir6zzb23@pd.tnic>
On 3/1/2017 12:40 PM, Borislav Petkov wrote:
> On Thu, Feb 16, 2017 at 09:48:25AM -0600, Tom Lendacky wrote:
>> This patch adds the support to check if SME has been enabled and if
>> memory encryption should be activated (checking of command line option
>> based on the configuration of the default state). If memory encryption
>> is to be activated, then the encryption mask is set and the kernel is
>> encrypted "in place."
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>> ---
>> arch/x86/kernel/head_64.S | 1 +
>> arch/x86/kernel/mem_encrypt_init.c | 71 +++++++++++++++++++++++++++++++++++-
>> arch/x86/mm/mem_encrypt.c | 2 +
>> 3 files changed, 73 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
>> index edd2f14..e6820e7 100644
>> --- a/arch/x86/kernel/head_64.S
>> +++ b/arch/x86/kernel/head_64.S
>> @@ -97,6 +97,7 @@ startup_64:
>> * Save the returned mask in %r12 for later use.
>> */
>> push %rsi
>> + movq %rsi, %rdi
>> call sme_enable
>> pop %rsi
>> movq %rax, %r12
>> diff --git a/arch/x86/kernel/mem_encrypt_init.c b/arch/x86/kernel/mem_encrypt_init.c
>> index 07cbb90..35c5e3d 100644
>> --- a/arch/x86/kernel/mem_encrypt_init.c
>> +++ b/arch/x86/kernel/mem_encrypt_init.c
>> @@ -19,6 +19,12 @@
>> #include <linux/mm.h>
>>
>> #include <asm/sections.h>
>> +#include <asm/processor-flags.h>
>> +#include <asm/msr.h>
>> +#include <asm/cmdline.h>
>> +
>> +static char sme_cmdline_arg_on[] __initdata = "mem_encrypt=on";
>> +static char sme_cmdline_arg_off[] __initdata = "mem_encrypt=off";
>>
>> extern void sme_encrypt_execute(unsigned long, unsigned long, unsigned long,
>> void *, pgd_t *);
>> @@ -217,8 +223,71 @@ unsigned long __init sme_get_me_mask(void)
>> return sme_me_mask;
>> }
>>
>> -unsigned long __init sme_enable(void)
>> +unsigned long __init sme_enable(void *boot_data)
>
> unsigned long __init sme_enable(struct boot_params *bp)
>
> works too.
Ok, will do.
>
> And then you need to correct the function signature in the
> !CONFIG_AMD_MEM_ENCRYPT case, at the end of this file, too:
>
> unsigned long __init sme_enable(struct boot_params *bp) { return 0; }
Yup, missed that. I'll make it match.
>
>> {
>> + struct boot_params *bp = boot_data;
>> + unsigned int eax, ebx, ecx, edx;
>> + unsigned long cmdline_ptr;
>> + bool enable_if_found;
>> + void *cmdline_arg;
>> + u64 msr;
>> +
>> + /* Check for an AMD processor */
>> + eax = 0;
>> + ecx = 0;
>> + native_cpuid(&eax, &ebx, &ecx, &edx);
>> + if ((ebx != 0x68747541) || (edx != 0x69746e65) || (ecx != 0x444d4163))
>> + goto out;
>> +
>> + /* Check for the SME support leaf */
>> + eax = 0x80000000;
>> + ecx = 0;
>> + native_cpuid(&eax, &ebx, &ecx, &edx);
>> + if (eax < 0x8000001f)
>> + goto out;
>> +
>> + /*
>> + * Check for the SME feature:
>> + * CPUID Fn8000_001F[EAX] - Bit 0
>> + * Secure Memory Encryption support
>> + * CPUID Fn8000_001F[EBX] - Bits 5:0
>> + * Pagetable bit position used to indicate encryption
>> + */
>> + eax = 0x8000001f;
>> + ecx = 0;
>> + native_cpuid(&eax, &ebx, &ecx, &edx);
>> + if (!(eax & 1))
>> + goto out;
>> +
>> + /* Check if SME is enabled */
>> + msr = native_read_msr(MSR_K8_SYSCFG);
>
> This native_read_msr() wankery is adding this check:
>
> if (msr_tracepoint_active(__tracepoint_read_msr))
>
> and here it is clearly too early for tracepoints. Please use __rdmsr()
> which is purely doing the MSR operation. (... and exception handling for
Ah, good catch. I'll switch to __rdmsr().
> when the RDMSR itself raises an exception but we're very early here too
> so the MSR better be there, otherwise we'll blow up).
Yes, it will be there if SME support is indicated in the CPUID result.
>
>> + if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
>> + goto out;
>> +
>> + /*
>> + * Fixups have not been to applied phys_base yet, so we must obtain
>
> ... not been applied to phys_base yet ...
Yup.
>
>> + * the address to the SME command line option in the following way.
>> + */
>> + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT)) {
>> + asm ("lea sme_cmdline_arg_off(%%rip), %0"
>> + : "=r" (cmdline_arg)
>> + : "p" (sme_cmdline_arg_off));
>> + enable_if_found = false;
>> + } else {
>> + asm ("lea sme_cmdline_arg_on(%%rip), %0"
>> + : "=r" (cmdline_arg)
>> + : "p" (sme_cmdline_arg_on));
>> + enable_if_found = true;
>> + }
>> +
>> + cmdline_ptr = bp->hdr.cmd_line_ptr | ((u64)bp->ext_cmd_line_ptr << 32);
>> +
>> + if (cmdline_find_option_bool((char *)cmdline_ptr, cmdline_arg))
>> + sme_me_mask = enable_if_found ? 1UL << (ebx & 0x3f) : 0;
>> + else
>> + sme_me_mask = enable_if_found ? 0 : 1UL << (ebx & 0x3f);
>
> I have a better idea: you can copy __cmdline_find_option() +
> cmdline_find_option() to arch/x86/lib/cmdline.c in a pre-patch. Then,
> pass in a buffer and check for "on" and "off". This way you don't
> have to misuse the _bool() variant for something which is actually
> "option=argument".
I can do that. Because phys_base hasn't been updated yet, I'll have to
create "on" and "off" constants and get their address in a similar way
to the command line option so that I can do the strncmp properly.
Thanks,
Tom
>
> Thanks.
>
next prev parent reply other threads:[~2017-03-07 16:08 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-16 15:41 [RFC PATCH v4 00/28] x86: Secure Memory Encryption (AMD) Tom Lendacky
2017-02-16 15:42 ` [RFC PATCH v4 01/28] x86: Documentation for AMD Secure Memory Encryption (SME) Tom Lendacky
2017-02-16 17:56 ` Borislav Petkov
2017-02-16 19:48 ` Tom Lendacky
2017-02-16 15:42 ` [RFC PATCH v4 02/28] x86: Set the write-protect cache mode for full PAT support Tom Lendacky
2017-02-17 11:07 ` Borislav Petkov
2017-02-17 15:56 ` Tom Lendacky
2017-02-16 15:42 ` [RFC PATCH v4 03/28] x86: Add the Secure Memory Encryption CPU feature Tom Lendacky
2017-02-16 18:13 ` Borislav Petkov
2017-02-16 19:42 ` Tom Lendacky
2017-02-16 20:06 ` Borislav Petkov
2017-02-16 15:42 ` [RFC PATCH v4 04/28] x86: Handle reduction in physical address size with SME Tom Lendacky
2017-02-17 11:04 ` Borislav Petkov
2017-02-16 15:43 ` [RFC PATCH v4 05/28] x86: Add Secure Memory Encryption (SME) support Tom Lendacky
2017-02-17 12:00 ` Borislav Petkov
2017-02-25 15:29 ` Borislav Petkov
2017-02-28 23:01 ` Tom Lendacky
2017-02-16 15:43 ` [RFC PATCH v4 06/28] x86: Add support to enable SME during early boot processing Tom Lendacky
2017-02-20 12:51 ` Borislav Petkov
2017-02-21 14:55 ` Tom Lendacky
2017-02-21 15:10 ` Borislav Petkov
2017-02-16 15:43 ` [RFC PATCH v4 07/28] x86: Provide general kernel support for memory encryption Tom Lendacky
2017-02-20 15:21 ` Borislav Petkov
2017-02-21 17:18 ` Tom Lendacky
2017-02-22 12:08 ` Borislav Petkov
2017-02-20 18:38 ` Borislav Petkov
2017-02-22 16:43 ` Tom Lendacky
2017-02-22 18:13 ` Dave Hansen
2017-02-23 23:12 ` Tom Lendacky
2017-02-22 18:13 ` Dave Hansen
2017-02-16 15:43 ` [RFC PATCH v4 08/28] x86: Extend the early_memremap support with additional attrs Tom Lendacky
2017-02-20 15:43 ` Borislav Petkov
2017-02-22 15:42 ` Tom Lendacky
2017-02-16 15:43 ` [RFC PATCH v4 09/28] x86: Add support for early encryption/decryption of memory Tom Lendacky
2017-02-20 18:22 ` Borislav Petkov
2017-02-22 15:48 ` Tom Lendacky
2017-02-16 15:44 ` [RFC PATCH v4 10/28] x86: Insure that boot memory areas are mapped properly Tom Lendacky
2017-02-20 19:45 ` Borislav Petkov
2017-02-22 18:34 ` Tom Lendacky
2017-02-16 15:44 ` [RFC PATCH v4 11/28] x86: Add support to determine the E820 type of an address Tom Lendacky
2017-02-20 20:09 ` Borislav Petkov
2017-02-28 22:34 ` Tom Lendacky
2017-03-03 9:52 ` Borislav Petkov
2017-02-16 15:44 ` [RFC PATCH v4 12/28] efi: Add an EFI table address match function Tom Lendacky
2017-02-16 15:44 ` [RFC PATCH v4 13/28] efi: Update efi_mem_type() to return defined EFI mem types Tom Lendacky
2017-02-21 12:05 ` Matt Fleming
2017-02-23 17:27 ` Tom Lendacky
2017-02-24 9:57 ` Matt Fleming
2017-02-16 15:45 ` [RFC PATCH v4 14/28] Add support to access boot related data in the clear Tom Lendacky
2017-02-21 15:06 ` Borislav Petkov
2017-02-23 21:34 ` Tom Lendacky
2017-02-24 10:21 ` Borislav Petkov
2017-02-24 15:04 ` Tom Lendacky
2017-02-24 15:22 ` Borislav Petkov
2017-03-08 6:55 ` Dave Young
2017-03-17 19:50 ` Tom Lendacky
2017-02-16 15:45 ` [RFC PATCH v4 15/28] Add support to access persistent memory " Tom Lendacky
2017-03-17 22:58 ` Elliott, Robert (Persistent Memory)
2017-03-23 21:02 ` Tom Lendacky
2017-02-16 15:45 ` [RFC PATCH v4 16/28] x86: Add support for changing memory encryption attribute Tom Lendacky
2017-02-22 18:52 ` Borislav Petkov
2017-02-28 22:46 ` Tom Lendacky
2017-02-16 15:45 ` [RFC PATCH v4 17/28] x86: Decrypt trampoline area if memory encryption is active Tom Lendacky
2017-02-16 15:46 ` [RFC PATCH v4 18/28] x86: DMA support for memory encryption Tom Lendacky
2017-02-25 17:10 ` Borislav Petkov
2017-03-06 17:47 ` Tom Lendacky
2017-02-16 15:46 ` [RFC PATCH v4 19/28] swiotlb: Add warnings for use of bounce buffers with SME Tom Lendacky
2017-02-17 15:59 ` Konrad Rzeszutek Wilk
2017-02-17 16:51 ` Tom Lendacky
2017-03-02 17:01 ` Paolo Bonzini
2017-02-27 17:52 ` Borislav Petkov
2017-02-28 23:19 ` Tom Lendacky
2017-03-01 11:17 ` Borislav Petkov
2017-02-16 15:46 ` [RFC PATCH v4 20/28] iommu/amd: Disable AMD IOMMU if memory encryption is active Tom Lendacky
2017-02-16 15:46 ` [RFC PATCH v4 21/28] x86: Check for memory encryption on the APs Tom Lendacky
2017-02-27 18:17 ` Borislav Petkov
2017-02-28 23:28 ` Tom Lendacky
2017-03-01 11:17 ` Borislav Petkov
2017-02-16 15:47 ` [RFC PATCH v4 22/28] x86: Do not specify encrypted memory for video mappings Tom Lendacky
2017-02-16 15:47 ` [RFC PATCH v4 23/28] x86/kvm: Enable Secure Memory Encryption of nested page tables Tom Lendacky
2017-02-16 15:47 ` [RFC PATCH v4 24/28] x86: Access the setup data through debugfs decrypted Tom Lendacky
2017-03-08 7:04 ` Dave Young
2017-03-17 19:54 ` Tom Lendacky
2017-02-16 15:47 ` [RFC PATCH v4 25/28] x86: Access the setup data through sysfs decrypted Tom Lendacky
2017-03-08 7:09 ` Dave Young
2017-03-17 20:09 ` Tom Lendacky
2017-02-16 15:47 ` [RFC PATCH v4 26/28] x86: Allow kexec to be used with SME Tom Lendacky
2017-02-17 15:57 ` Konrad Rzeszutek Wilk
2017-02-17 16:43 ` Tom Lendacky
2017-03-01 9:25 ` Dave Young
2017-03-01 9:27 ` Dave Young
2017-03-06 17:58 ` Tom Lendacky
2017-03-06 18:04 ` Tom Lendacky
2017-03-08 8:12 ` Dave Young
2017-02-28 10:35 ` Borislav Petkov
2017-03-01 15:36 ` Tom Lendacky
2017-02-16 15:48 ` [RFC PATCH v4 27/28] x86: Add support to encrypt the kernel in-place Tom Lendacky
2017-03-01 17:36 ` Borislav Petkov
2017-03-02 18:30 ` Tom Lendacky
2017-03-02 18:51 ` Borislav Petkov
2017-02-16 15:48 ` [RFC PATCH v4 28/28] x86: Add support to make use of Secure Memory Encryption Tom Lendacky
2017-03-01 18:40 ` Borislav Petkov
2017-03-07 16:05 ` Tom Lendacky [this message]
2017-03-07 17:42 ` Borislav Petkov
2017-03-08 15:05 ` Borislav Petkov
2017-02-18 18:12 ` [RFC PATCH v4 00/28] x86: Secure Memory Encryption (AMD) Borislav Petkov
2017-02-21 15:09 ` Tom Lendacky
2017-02-21 17:42 ` Rik van Riel
2017-02-21 17:53 ` Borislav Petkov
2017-03-01 9:17 ` Dave Young
2017-03-01 17:51 ` Tom Lendacky
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