[MODERATED] Re: [PATCH v4 05/10] TAAv4 5

[Pawan Gupta <pawan.kumar.gupta@linux.intel.com>]

On Tue, Sep 03, 2019 at 02:15:33PM -0700, speck for Pawan Gupta wrote:
> From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Subject: [PATCH v4 05/10] x86/speculation/mds: Rename MDS buffer clear
>  functions
> 
> In preparation for reusing the MDS cpu buffer clear functions and static
> keys by the following commits, rename them from mds_* --> verw_* to make
> them more generic.  VERW is a legacy cpu instruction which was
> overloaded to clear the CPU buffers for MDS.
> 
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> ---
>  Documentation/x86/mds.rst            |  6 +++---
>  arch/x86/entry/common.c              |  2 +-
>  arch/x86/include/asm/irqflags.h      |  4 ++--
>  arch/x86/include/asm/mwait.h         |  4 ++--
>  arch/x86/include/asm/nospec-branch.h | 24 ++++++++++++------------
>  arch/x86/kernel/cpu/bugs.c           | 22 +++++++++++-----------
>  arch/x86/kernel/nmi.c                |  2 +-
>  arch/x86/kvm/vmx/vmx.c               |  4 ++--
>  8 files changed, 34 insertions(+), 34 deletions(-)

This patch (s/mds/verw/) doesn't add much value compared to the amount
of changes needed. It also doesn't bring any functional change. Dropping
this patch in favor of below comment.

taa_select_mitigation()
{
	[...]
	/*
	 * TSX is enabled, select alternate mitigation for TAA which is
	 * same as MDS. Enable MDS static branch to clear CPU buffers.
	 *
	 * For guests that can't determine whether the correct microcode is
	 * present on host, enable the mitigation for UCODE_NEEDED as well.
	 */
	static_branch_enable(&mds_user_clear);

Thanks,
Pawan