On Wed, Sep 23, 2020 at 09:41:33AM -0700, Dan Williams wrote: > The rename replaces a single top-level memcpy_mcsafe() with either > copy_mc_to_user(), or copy_mc_to_kernel(). What is "copy_mc" supposed to mean? Especially if it is called that on two arches... > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 7101ac64bb20..e876b3a087f9 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -75,7 +75,7 @@ config X86 > select ARCH_HAS_PTE_DEVMAP if X86_64 > select ARCH_HAS_PTE_SPECIAL > select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 > - select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE > + select ARCH_HAS_COPY_MC if X86_64 X86_MCE is dropped here. So if I have a build which has # CONFIG_X86_MCE is not set One of those quirks like: /* * CAPID0{7:6} indicate whether this is an advanced RAS SKU * CAPID5{8:5} indicate that various NVDIMM usage modes are * enabled, so memory machine check recovery is also enabled. */ if ((capid0 & 0xc0) == 0xc0 || (capid5 & 0x1e0)) enable_copy_mc_fragile(); will still call enable_copy_mc_fragile() and none of those platforms need MCE functionality? But there's a hunk in here which sets it in the MCE code: if (mca_cfg.recovery) enable_copy_mc_fragile(); So which is it? They need it or they don't? The comment over copy_mc_to_kernel() says: * Call into the 'fragile' version on systems that have trouble * actually do machine check recovery If CONFIG_X86_MCE is not set, I'll say. :) > +++ b/arch/x86/lib/copy_mc.c > @@ -0,0 +1,66 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright(c) 2016-2020 Intel Corporation. All rights reserved. */ > + > +#include <linux/jump_label.h> > +#include <linux/uaccess.h> > +#include <linux/export.h> > +#include <linux/string.h> > +#include <linux/types.h> > + > +static DEFINE_STATIC_KEY_FALSE(copy_mc_fragile_key); > + > +void enable_copy_mc_fragile(void) > +{ > + static_branch_inc(©_mc_fragile_key); > +} > + > +/** > + * copy_mc_to_kernel - memory copy that that handles source exceptions One "that" is enough. ... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette