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From: Wei Liu <wl@xen.org>
To: "Durrant, Paul" <pdurrant@amazon.co.uk>
Cc: "Wei Liu" <liuwe@microsoft.com>, "Wei Liu" <wl@xen.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Michael Kelley" <mikelley@microsoft.com>,
	"Jan Beulich" <jbeulich@suse.com>,
	"Xen Development List" <xen-devel@lists.xenproject.org>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 2/4] x86/hypervisor: pass flags to hypervisor_flush_tlb
Date: Thu, 13 Feb 2020 10:29:16 +0000	[thread overview]
Message-ID: <20200213102916.pth227it5jozbp22@debian> (raw)
In-Reply-To: <0fd1bb31e2054ddeb5e21793aa0c8750@EX13D32EUC003.ant.amazon.com>

On Thu, Feb 13, 2020 at 08:48:39AM +0000, Durrant, Paul wrote:
> > -----Original Message-----
> > From: Roger Pau Monné <roger.pau@citrix.com>
> > Sent: 12 February 2020 18:01
> > To: Wei Liu <wl@xen.org>
> > Cc: Xen Development List <xen-devel@lists.xenproject.org>; Durrant, Paul
> > <pdurrant@amazon.co.uk>; Michael Kelley <mikelley@microsoft.com>; Wei Liu
> > <liuwe@microsoft.com>; Jan Beulich <jbeulich@suse.com>; Andrew Cooper
> > <andrew.cooper3@citrix.com>
> > Subject: Re: [PATCH 2/4] x86/hypervisor: pass flags to
> > hypervisor_flush_tlb
> > 
> > On Wed, Feb 12, 2020 at 04:09:16PM +0000, Wei Liu wrote:
> > > Hyper-V's L0 assisted flush has fine-grained control over what gets
> > > flushed. We need all the flags available to make the best decisions
> > > possible.
> > >
> > > No functional change because Xen's implementation doesn't care about
> > > what is passed to it.
> > 
> > While it's certainly fine to pass a flags field with more information,
> > the flush flags for Xen can also contain FLUSH_CACHE, FLUSH_VCPU_STATE
> > or FLUSH_ROOT_PGTBL, can you add an assert that those never get passed
> > to the flush hook?
> > 
> > IMO we should define a mask with FLUSH_TLB, FLUSH_TLB_GLOBAL,
> > FLUSH_VA_VALID and FLUSH_ORDER_MASK and assert that those are the only
> > valid flags to be used for the hypervisor assisted flush hook.
> >
> 
> Agreed that this should be abstracted; we certainly don't want to have
> various bits of Xen needing to know what hypervisor it is running on
> top of.

OK. I can introduce a FLUSH_TLB_FLAGS for all things pertaining to TLB
-- the four things mentioned in Roger's reply.

Wei.

> 
>   Paul
> 
>  
> > Thanks, Roger.

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  reply	other threads:[~2020-02-13 10:29 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 16:09 [Xen-devel] [PATCH 0/4] Xen on Hyper-V: Implement L0 assisted TLB flush Wei Liu
2020-02-12 16:09 ` [Xen-devel] [PATCH 1/4] x86/hyperv: misc cleanup Wei Liu
2020-02-12 16:53   ` Roger Pau Monné
2020-02-13 10:30     ` Wei Liu
2020-02-13  8:43   ` Durrant, Paul
2020-02-13  9:46   ` Jan Beulich
2020-02-13 12:24     ` Wei Liu
2020-02-13 13:32       ` Jan Beulich
2020-02-12 16:09 ` [Xen-devel] [PATCH 2/4] x86/hypervisor: pass flags to hypervisor_flush_tlb Wei Liu
2020-02-12 17:00   ` Roger Pau Monné
2020-02-13  8:48     ` Durrant, Paul
2020-02-13 10:29       ` Wei Liu [this message]
2020-02-13 11:56         ` Wei Liu
2020-02-12 16:09 ` [Xen-devel] [PATCH 3/4] x86/hyperv: skeleton for L0 assisted TLB flush Wei Liu
2020-02-12 17:09   ` Roger Pau Monné
2020-02-12 23:01     ` Wei Liu
2020-02-12 16:09 ` [Xen-devel] [PATCH 4/4] x86/hyperv: " Wei Liu
2020-02-12 17:43   ` Roger Pau Monné
2020-02-13  9:49     ` Jan Beulich
2020-02-13 12:25       ` Wei Liu
2020-02-13 12:20     ` Wei Liu
2020-02-13 12:41       ` Roger Pau Monné
2020-02-14 10:47         ` Wei Liu

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