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Re: [Xen-devel] [PATCH SpectreV1+L1TF v4 01/11] is_control_domain: block speculation
- To: Jan Beulich <JBeulich@xxxxxxxx>, nmanthey@xxxxxxxxx
- From: Julien Grall <julien.grall@xxxxxxx>
- Date: Wed, 23 Jan 2019 13:20:04 +0000
- Cc: Tim Deegan <tim@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wei.liu2@xxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>, Dario Faggioli <dfaggioli@xxxxxxxx>, Martin Pohlack <mpohlack@xxxxxxxxx>, David Woodhouse <dwmw@xxxxxxxxxxxx>, "Martin Mazein\(amazein\)" <amazein@xxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Julian Stecklina <jsteckli@xxxxxxxxx>, Bjoern Doebel <doebel@xxxxxxxxx>
- Delivery-date: Wed, 23 Jan 2019 13:20:16 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
Hi,
On 23/01/2019 13:07, Jan Beulich wrote:
On 23.01.19 at 12:51, <nmanthey@xxxxxxxxx> wrote:
--- a/xen/include/xen/nospec.h
+++ b/xen/include/xen/nospec.h
@@ -58,6 +58,21 @@ static inline unsigned long array_index_mask_nospec(unsigned
long index,
(typeof(_i)) (_i & _mask); \
})
+/*
+ * allow to insert a read memory barrier into conditionals
+ */
Please obey to the comment style set forth in ./CODING_STYLE.
+#ifdef CONFIG_X86
+static inline bool lfence_true(void) { rmb(); return true; }
+#else
+static inline bool lfence_true(void) { return true; }
+#endif
This is a generic header, hence functions defined here should have
universally applicable names. "lfence", however, is an x86 term
(naming a particular instruction). I can't think of really good
alternatives, but how about one of arch_nospec_true() /
arch_fence_nospec_true() / arch_nospec_fence_true()?
We seems to use more the term "barrier" in common code over "fence". So how
about arch_barrier_nospec_true/arch_nospec_barrier_true?
Cheers,
--
Julien Grall
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