From: Paul Mackerras <paulus@samba.org>
To: Alexander Graf <agraf@suse.de>
Cc: Cedric Le Goater <clg@fr.ibm.com>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org mailing list" <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests
Date: Wed, 6 Nov 2013 16:55:37 +1100 [thread overview]
Message-ID: <20131106055537.GH14842@drongo> (raw)
In-Reply-To: <84018BDE-858B-4F59-8AA0-9135CCFF4720@suse.de>
On Tue, Nov 05, 2013 at 02:01:14PM +0100, Alexander Graf wrote:
>
> On 05.11.2013, at 13:28, Cedric Le Goater <clg@fr.ibm.com> wrote:
>
> > +/*
> > + * Compare endian order of host and guest to determine whether we need
> > + * to byteswap or not
> > + */
> > static inline bool kvmppc_need_byteswap(struct kvm_vcpu *vcpu)
> > {
> > - return vcpu->arch.shared->msr & MSR_LE;
> > + return ((mfmsr() & (MSR_LE)) >> MSR_LE_LG) ^
>
> mfmsr() is slow. Just use #ifdef __LITTLE_ENDIAN__.
Or (MSR_KERNEL & MSR_LE).
> > + /* if we are loading data from a guest which is in Split
> > + * Little Endian mode, the byte order is reversed
>
> Only for data. Instructions are still non-reverse. You express this well in the code, but not in the comment.
Well, his comment does say "if we are loading data", but I agree it's
slightly ambiguous (the guest's instructions are our data).
Paul.
next prev parent reply other threads:[~2013-11-06 5:55 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-08 14:12 [PATCH v2 0/3] KVM: PPC: Book3S: MMIO support for Little Endian guests Cédric Le Goater
2013-10-08 14:12 ` [PATCH v2 1/3] KVM: PPC: Book3S: add helper routine to load guest instructions Cédric Le Goater
2013-10-08 14:12 ` [PATCH v2 2/3] KVM: PPC: Book3S: add helper routines to detect endian Cédric Le Goater
2013-10-08 14:12 ` [PATCH v2 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests Cédric Le Goater
2013-10-08 14:25 ` Alexander Graf
2013-10-08 15:07 ` Cedric Le Goater
2013-10-08 15:31 ` [PATCH v3 " Cédric Le Goater
2013-10-08 15:36 ` Alexander Graf
2013-10-08 16:10 ` Cedric Le Goater
2013-10-08 16:43 ` [PATCH v4 0/3] KVM: PPC: Book3S: MMIO support for Little Endian guests Cédric Le Goater
2013-10-08 16:43 ` [PATCH v4 1/3] KVM: PPC: Book3S: add helper routine to load guest instructions Cédric Le Goater
2013-10-08 16:43 ` [PATCH v4 2/3] KVM: PPC: Book3S: add helper routines to detect endian order Cédric Le Goater
2013-10-08 16:43 ` [PATCH v4 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests Cédric Le Goater
2013-10-08 23:31 ` [PATCH v2 " Paul Mackerras
2013-10-08 23:46 ` Alexander Graf
2013-10-09 5:59 ` Paul Mackerras
2013-10-09 8:29 ` Alexander Graf
2013-10-09 8:42 ` Cedric Le Goater
2013-10-10 10:16 ` Paul Mackerras
2013-11-04 11:44 ` Alexander Graf
2013-11-05 12:28 ` Cedric Le Goater
2013-11-05 13:01 ` Alexander Graf
2013-11-05 17:22 ` [PATCH v5 0/6] KVM: PPC: Book3S: MMIO support for Little Endian guests Cédric Le Goater
2013-11-05 17:22 ` [PATCH v5 1/6] KVM: PPC: Book3S: add helper routine to load guest instructions Cédric Le Goater
2013-11-05 17:22 ` [PATCH v5 2/6] KVM: PPC: Book3S: add helper routines to detect endian Cédric Le Goater
2014-01-02 20:05 ` Alexander Graf
2014-01-08 17:22 ` Cedric Le Goater
2013-11-05 17:22 ` [PATCH v5 3/6] KVM: PPC: Book3S: MMIO emulation support for little endian guests Cédric Le Goater
2014-01-02 20:22 ` Alexander Graf
2014-01-08 17:23 ` Cedric Le Goater
2014-01-08 17:34 ` Alexander Graf
2014-01-08 17:40 ` Cedric Le Goater
2014-01-08 17:35 ` [PATCH v6] " Cédric Le Goater
2014-01-09 10:02 ` [PATCH v7] " Cédric Le Goater
2014-01-09 10:17 ` Alexander Graf
2014-01-09 10:33 ` Cedric Le Goater
2014-01-09 10:51 ` [PATCH v8] " Cédric Le Goater
2014-01-09 10:55 ` Alexander Graf
2013-11-05 17:22 ` [PATCH v5 4/6] KVM: PPC: Book3S: modify kvmppc_need_byteswap() for little endian host Cédric Le Goater
2013-11-08 14:36 ` [PATCH v5.1 " Cedric Le Goater
2014-01-02 20:28 ` Alexander Graf
2014-01-02 20:25 ` [PATCH v5 " Alexander Graf
2013-11-05 17:22 ` [PATCH v5 5/6] powerpc: add Split Little Endian bit to MSR Cédric Le Goater
2013-11-05 17:22 ` [PATCH v5 6/6] KVM: PPC: Book3S: modify byte loading when guest uses Split Little Endian Cédric Le Goater
2014-01-02 20:26 ` Alexander Graf
2013-11-06 5:55 ` Paul Mackerras [this message]
2013-11-08 14:29 ` [PATCH v2 3/3] KVM: PPC: Book3S: MMIO emulation support for little endian guests Cedric Le Goater
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