Cc: brijesh.singh@amd.com, Tom Lendacky <thomas.lendacky@amd.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
        David Laight <David.Laight@aculab.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Matt Fleming <matt@codeblueprint.co.uk>,
        David Howells <dhowells@redhat.com>, Paul Mackerras <paulus@samba.org>,
        Christoph Lameter <cl@linux.com>, Jonathan Corbet <corbet@lwn.net>,
        =?UTF-8?Q?Radim_Krcm=c3=a1r?= <rkrcmar@redhat.com>,
        Piotr Luc <piotr.luc@intel.com>, Ingo Molnar <mingo@redhat.com>,
        Dave Airlie <airlied@redhat.com>, Kees Cook <keescook@chromium.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Reza Arbab <arbab@linux.vnet.ibm.com>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Laura Abbott <labbott@redhat.com>, Tony Luck <tony.luck@intel.com>,
        Ard.Biesheuvel@zytor.com
Subject: Re: [RFC Part1 PATCH v3 13/17] x86/io: Unroll string I/O when SEV is
 active
To: Borislav Petkov <bp@suse.de>
References: <20170724190757.11278-1-brijesh.singh@amd.com>
 <20170724190757.11278-14-brijesh.singh@amd.com>
 <063D6719AE5E284EB5DD2968C1650D6DD003FB85@AcuExch.aculab.com>
 <CAK8P3a3h7JpmkW7W=HwqAuWWmro=ngj6HSeiiML_=T82x-FtZQ@mail.gmail.com>
 <ed6d4ce7-97a6-f664-d7d7-4ff48bc6f06a@amd.com>
 <201707261927.v6QJR228008075@mail.zytor.com>
 <589d65a4-eb09-bae9-e8b4-a2d78ca6b509@amd.com>
 <20170822165248.rkbluikdgduu7ucy@pd.tnic>
 <20170915122430.pnroy6vsg53warel@pd.tnic>
 <95314c89-2620-8bb7-cbe8-cd9bc3adabb0@amd.com>
 <20170915143935.6vtfp5rtj5h324fi@pd.tnic>
From: Brijesh Singh <brijesh.singh@amd.com>
Message-ID: <ad628a45-8e4e-9cfc-2cc4-33dc6bf4613a@amd.com>
Date: Fri, 15 Sep 2017 09:48:53 -0500
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On 09/15/2017 09:40 AM, Borislav Petkov wrote:
> I need to figure out the include hell first.

I am working with slightly newer patch sets -- in that patch Tom has
moved the sev_active() definition in arch/x86/mm/mem_encrypt.c and I
have no issue using your recommended (since I no longer need the include
path changes).

But in my quick run I did found a runtime issue, it seems enabling the static
key in sme_enable is too early. Guest reboots as soon as it tries to enable
the key.

I see the similar issue with non SEV guest with my simple patch below.
Guest will reboot as soon as it tries to enable the key.

--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -40,6 +40,8 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
  
  #define __head __section(.head.text)
  
+DEFINE_STATIC_KEY_FALSE(__testme);
+
  static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
  {
         return ptr - (void *)_text + (void *)physaddr;
@@ -71,6 +73,8 @@ unsigned long __head __startup_64(unsigned long physaddr,
         if (load_delta & ~PMD_PAGE_MASK)
                 for (;;);
  
+       static_branch_enable(&__testme);
+
         /* Activate Secure Memory Encryption (SME) if supported and enabled */
         sme_enable(bp);