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Message-ID: <063D6719AE5E284EB5DD2968C1650D6DD003FB85@AcuExch.aculab.com>
Date: Tue, 25 Jul 2017 09:51:13 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Brijesh Singh' <brijesh.singh@....com>,
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CC: Fenghua Yu <fenghua.yu@...el.com>,
Matt Fleming <matt@...eblueprint.co.uk>,
David Howells <dhowells@...hat.com>,
"Paul Mackerras" <paulus@...ba.org>,
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Lu Baolu <baolu.lu@...ux.intel.com>
Subject: RE: [RFC Part1 PATCH v3 13/17] x86/io: Unroll string I/O when SEV
is active
From: Brijesh Singh
> Sent: 24 July 2017 20:08
> From: Tom Lendacky <thomas.lendacky@....com>
>
> Secure Encrypted Virtualization (SEV) does not support string I/O, so
> unroll the string I/O operation into a loop operating on one element at
> a time.
>
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
> arch/x86/include/asm/io.h | 26 ++++++++++++++++++++++----
> 1 file changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
> index e080a39..2f3c002 100644
> --- a/arch/x86/include/asm/io.h
> +++ b/arch/x86/include/asm/io.h
> @@ -327,14 +327,32 @@ static inline unsigned type in##bwl##_p(int port) \
> \
> static inline void outs##bwl(int port, const void *addr, unsigned long count) \
> {
Is it even worth leaving these as inline functions?
Given the speed of IO cycles it is unlikely that the cost of calling a real
function will be significant.
The code bloat reduction will be significant.
David
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