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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Sergey Dyasli <sergey.dyasli@citrix.com>,
	Wei Liu <wei.liu2@citrix.com>, Jan Beulich <JBeulich@suse.com>,
	Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH v2 4/5] x86/hvm: Handle x2apic MSRs via the new guest_{rd, wr}msr() infrastructure
Date: Mon, 10 Sep 2018 16:45:10 +0200	[thread overview]
Message-ID: <20180910144510.3jszudlfmragp3k2@mac.bytemobile.com> (raw)
In-Reply-To: <1520449116-15443-5-git-send-email-andrew.cooper3@citrix.com>

On Wed, Mar 07, 2018 at 06:58:35PM +0000, Andrew Cooper wrote:
> Dispatch from the guest_{rd,wr}msr() functions.  The read side should be safe
> outside of current context, but the write side is definitely not.  As the
> toolstack has no legitimate reason to access the APIC registers via this
> interface (not least because whether they are accessible at all depends on
> guest settings), unilaterally reject access attempts outside of current
> context.
> 
> Rename to guest_{rd,wr}msr_x2apic() for consistency, and alter the functions
> to use X86EMUL_EXCEPTION rather than X86EMUL_UNHANDLEABLE.  The previous
> callers turned UNHANDLEABLE into EXCEPTION, but using UNHANDLEABLE will now
> interfere with the fallback to legacy MSR handling.
> 
> While altering guest_rdmsr_x2apic() make a couple of minor improvements.
> Reformat the initialiser for readable[] so it indents in a more natural way,
> and alter high to be a 64bit integer to avoid shifting 0 by 32 in the common
> path.
> 
> Observant people might notice that we now don't let PV guests read the x2apic
> MSRs.  They should never have been able to in the first place.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Roger.

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  parent reply	other threads:[~2018-09-10 14:45 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-07 18:58 [PATCH v2 0/5] x86: Switch some bits of MSR handing over to the new infrastructure Andrew Cooper
2018-03-07 18:58 ` [PATCH v2 1/5] x86/hvm: Handle viridian MSRs via the new guest_{rd, wr}msr() infrastructure Andrew Cooper
2018-03-13 15:00   ` Jan Beulich
2018-03-13 15:20   ` Jan Beulich
2018-03-13 15:47     ` Andrew Cooper
2018-03-13 16:25       ` Jan Beulich
2018-03-07 18:58 ` [PATCH v2 2/5] x86: Handle the Xen " Andrew Cooper
2018-03-13 15:04   ` Jan Beulich
2018-09-07 14:30     ` Andrew Cooper
2018-09-07 15:47       ` Jan Beulich
2018-09-07 16:01         ` Andrew Cooper
2018-09-10  9:44           ` Jan Beulich
2018-03-07 18:58 ` [PATCH v2 3/5] x86: Fix APIC MSR constant names Andrew Cooper
2018-03-07 20:59   ` Konrad Rzeszutek Wilk
2018-03-08  1:26   ` Tian, Kevin
2018-03-13 15:15   ` Jan Beulich
2018-09-10 14:39   ` Roger Pau Monné
2018-03-07 18:58 ` [PATCH v2 4/5] x86/hvm: Handle x2apic MSRs via the new guest_{rd, wr}msr() infrastructure Andrew Cooper
2018-03-07 20:59   ` Konrad Rzeszutek Wilk
2018-03-13 15:21     ` Jan Beulich
2018-09-10 14:45   ` Roger Pau Monné [this message]
2018-03-07 18:58 ` [PATCH v2 5/5] x86/msr: Blacklist various MSRs which guests definitely shouldn't be using Andrew Cooper
2018-03-07 21:01   ` Konrad Rzeszutek Wilk
2018-03-13 15:35   ` Jan Beulich

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