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| author | Joerg Roedel <jroedel@suse.de> | 2018-07-18 11:41:15 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-20 01:11:48 +0200 |
| commit | 5e8105950a8b3e03e805299b4d05020ee4eda31a (patch) | |
| tree | e5ab66cb17129a284934830bf40eda4b7ebfcff8 /arch/x86 | |
| parent | x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32 (diff) | |
| download | linux-5e8105950a8b3e03e805299b4d05020ee4eda31a.tar.xz linux-5e8105950a8b3e03e805299b4d05020ee4eda31a.zip | |
x86/mm/pti: Add Warning when booting on a PCID capable CPU
Warn the user in case the performance can be significantly improved by
switching to a 64-bit kernel.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-39-git-send-email-joro@8bytes.org
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/mm/pti.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index a536ecc91847..7b1c85759005 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -517,6 +517,28 @@ void __init pti_init(void) pr_info("enabled\n"); +#ifdef CONFIG_X86_32 + /* + * We check for X86_FEATURE_PCID here. But the init-code will + * clear the feature flag on 32 bit because the feature is not + * supported on 32 bit anyway. To print the warning we need to + * check with cpuid directly again. + */ + if (cpuid_ecx(0x1) && BIT(17)) { + /* Use printk to work around pr_fmt() */ + printk(KERN_WARNING "\n"); + printk(KERN_WARNING "************************************************************\n"); + printk(KERN_WARNING "** WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! **\n"); + printk(KERN_WARNING "** **\n"); + printk(KERN_WARNING "** You are using 32-bit PTI on a 64-bit PCID-capable CPU. **\n"); + printk(KERN_WARNING "** Your performance will increase dramatically if you **\n"); + printk(KERN_WARNING "** switch to a 64-bit kernel! **\n"); + printk(KERN_WARNING "** **\n"); + printk(KERN_WARNING "** WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! **\n"); + printk(KERN_WARNING "************************************************************\n"); + } +#endif + pti_clone_user_shared(); /* Undo all global bits from the init pagetables in head_64.S: */ |