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From: Juergen Gross <jgross@suse.com>
To: xen-devel@lists.xen.org
Cc: Juergen Gross <jgross@suse.com>,
	sstabellini@kernel.org, wei.liu2@citrix.com,
	George.Dunlap@eu.citrix.com, andrew.cooper3@citrix.com,
	ian.jackson@eu.citrix.com, tim@xen.org, julien.grall@arm.com,
Subject: [PATCH v2 0/2] Support consistent reads of mapped vcpu_runstate_info
Date: Wed, 15 Jun 2016 13:34:37 +0200	[thread overview]
Message-ID: <1465990479-20657-1-git-send-email-jgross@suse.com> (raw)

A guest mapping vcpu_runstate_info into its memory can't read this
information from another cpu but the one the data is referring to.
Reason is there is no reliable way for the guest to detect a concurrent
data update by the hypervisor.

This patch series adds an update flag to the mapped data which can be
used by the guest to detect an update is occurring. As this flag is
modifying the current interface it has to be activated by using a
vm_assist hypercall, which in turn has to be made available for ARM.

Runtime tested on x86 with a modified Linux kernel using the new
Compile tested only for ARM.

Changes in V2:
- patch 1: readded the #ifdef's as requested by Jan Beulich
- patch 2: smp_wmb() instead of wmb() as requested by Andrew Cooper
- patch 2: use sizeof() as requested by Jan Beulich
- patch 2: eliminate new variable update_flag as requested by Jan Beulich

Juergen Gross (2):
  xen/arm: add support for vm_assist hypercall
  xen: add update indicator to vcpu_runstate_info

 xen/arch/arm/domain.c        | 21 +++++++++++++++++++++
 xen/arch/arm/traps.c         |  1 +
 xen/arch/x86/domain.c        | 30 ++++++++++++++++++++++++++++++
 xen/include/asm-arm/config.h |  2 ++
 xen/include/asm-x86/config.h |  1 +
 xen/include/public/vcpu.h    |  6 ++++++
 xen/include/public/xen.h     |  7 +++++++
 7 files changed, 68 insertions(+)


Xen-devel mailing list

             reply	other threads:[~2016-06-15 11:34 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-15 11:34 Juergen Gross [this message]
2016-06-15 11:34 ` [PATCH v2 1/2] xen/arm: add support for vm_assist hypercall Juergen Gross
2016-06-15 11:34 ` [PATCH v2 2/2] xen: add update indicator to vcpu_runstate_info Juergen Gross
2016-06-16 11:15   ` Jan Beulich
     [not found]   ` <5762A66A02000078000F5A39@suse.com>
2016-06-16 12:11     ` Juergen Gross
2016-06-16 12:36       ` Jan Beulich
     [not found]       ` <5762B96102000078000F5ADE@suse.com>
2016-06-16 14:36         ` Juergen Gross

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