From: Suraj Jitindar Singh <sjitindarsingh@gmail.com> To: Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@lists.ozlabs.org Cc: kvm-ppc@vger.kernel.org, benh@kernel.crashing.org, paulus@samba.org, agraf@suse.com Subject: Re: [PATCH V3 1/2] powerpc: Define new ISA v3.00 logical PVR value and PCR register value Date: Fri, 11 Nov 2016 17:11:53 +1100 [thread overview] Message-ID: <1478844713.2189.1.camel@gmail.com> (raw) In-Reply-To: <874m3fk4e7.fsf@concordia.ellerman.id.au> On Thu, 2016-11-10 at 21:36 +1100, Michael Ellerman wrote: > Suraj Jitindar Singh <sjitindarsingh@gmail.com> writes: > > > > > On Tue, 2016-11-08 at 19:21 +1100, Michael Ellerman wrote: > > > > > > Suraj Jitindar Singh <sjitindarsingh@gmail.com> writes: > > > > > > > > > > > > > > > ISA 3.00 adds the logical PVR value 0x0f000005, so add a > > > > definition > > > > for > > > > this. > > > > > > > > Define PCR_ARCH_207 to reflect ISA 2.07 compatibility mode in > > > > the > > > > processor > > > > compatibility register (PCR). Also define a dummy ISA 3.00 > > > > compatibility > > > > mode PCR_ARCH_300 to be used in the next patch to help with > > > > determining the > > > > PCR value. > > > What's "dummy" about the PCR value? > > > > Then next patch needs some PCR bit to specify that we want to > > emulate > > v3.00 and/or that the host can emulate v3.00 to follow the pattern > > used > > to determine that the host is capable of emulating the given compat > > level and for determining which PCR bits to set. But no such bit is > > defined for V3.00 compat mode yet so a "dummy" one is used to > > represent > > this even though it's never defined in the ISA. > > > > > > > > > AFAICS that value is reserved in the ISA. > > > > Yes it is a reserved bit in the PCR register but it will never > > actually > > be set, it will always be cleared by "host_pcr_bit - > > guest_pcr_bit;" > > > > > > > > > > > Are we assuming/hoping that ISA 4.0 will use 0x10 to mean ISA 3.0 > > > ? > > > > Basically yes, and although I know nothing's given, it would follow > > the > > current pattern for whatever the next ISA version is to use 0x10 to > > mean V3.00 compat mode. Otherwise this will need to be updated at > > some > > point when that's released... In fact if the compat bits are no > > longer > > sequential this will need rewriting. > > OK thanks. > > Please send a v4 with that detail in a comment and a better > explanation > in the change log. > > I think a block comment before the #define would be best, ie. > something Will do and send a V4 > like: > > #define PCR_ARCH_207 0x8 /* Architecture 2.07 > */ > > /* > * All that helpful detail from above ... > */ > #define PCR_ARCH_300 0x10 > > > We should also ask if we can get 0x10 reserved in the ISA to mean > 3.00. Probably a good idea, might ask you about the process for this on Monday... > > cheers
WARNING: multiple messages have this Message-ID (diff)
From: Suraj Jitindar Singh <sjitindarsingh@gmail.com> To: Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@lists.ozlabs.org Cc: kvm-ppc@vger.kernel.org, benh@kernel.crashing.org, paulus@samba.org, agraf@suse.com Subject: Re: [PATCH V3 1/2] powerpc: Define new ISA v3.00 logical PVR value and PCR register value Date: Fri, 11 Nov 2016 06:11:53 +0000 [thread overview] Message-ID: <1478844713.2189.1.camel@gmail.com> (raw) In-Reply-To: <874m3fk4e7.fsf@concordia.ellerman.id.au> On Thu, 2016-11-10 at 21:36 +1100, Michael Ellerman wrote: > Suraj Jitindar Singh <sjitindarsingh@gmail.com> writes: > > > > > On Tue, 2016-11-08 at 19:21 +1100, Michael Ellerman wrote: > > > > > > Suraj Jitindar Singh <sjitindarsingh@gmail.com> writes: > > > > > > > > > > > > > > > ISA 3.00 adds the logical PVR value 0x0f000005, so add a > > > > definition > > > > for > > > > this. > > > > > > > > Define PCR_ARCH_207 to reflect ISA 2.07 compatibility mode in > > > > the > > > > processor > > > > compatibility register (PCR). Also define a dummy ISA 3.00 > > > > compatibility > > > > mode PCR_ARCH_300 to be used in the next patch to help with > > > > determining the > > > > PCR value. > > > What's "dummy" about the PCR value? > > > > Then next patch needs some PCR bit to specify that we want to > > emulate > > v3.00 and/or that the host can emulate v3.00 to follow the pattern > > used > > to determine that the host is capable of emulating the given compat > > level and for determining which PCR bits to set. But no such bit is > > defined for V3.00 compat mode yet so a "dummy" one is used to > > represent > > this even though it's never defined in the ISA. > > > > > > > > > AFAICS that value is reserved in the ISA. > > > > Yes it is a reserved bit in the PCR register but it will never > > actually > > be set, it will always be cleared by "host_pcr_bit - > > guest_pcr_bit;" > > > > > > > > > > > Are we assuming/hoping that ISA 4.0 will use 0x10 to mean ISA 3.0 > > > ? > > > > Basically yes, and although I know nothing's given, it would follow > > the > > current pattern for whatever the next ISA version is to use 0x10 to > > mean V3.00 compat mode. Otherwise this will need to be updated at > > some > > point when that's released... In fact if the compat bits are no > > longer > > sequential this will need rewriting. > > OK thanks. > > Please send a v4 with that detail in a comment and a better > explanation > in the change log. > > I think a block comment before the #define would be best, ie. > something Will do and send a V4 > like: > > #define PCR_ARCH_207 0x8 /* Architecture 2.07 > */ > > /* > * All that helpful detail from above ... > */ > #define PCR_ARCH_300 0x10 > > > We should also ask if we can get 0x10 reserved in the ISA to mean > 3.00. Probably a good idea, might ask you about the process for this on Monday... > > cheers
next prev parent reply other threads:[~2016-11-11 6:12 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-11-01 4:41 [PATCH V3 0/2] powerpc: add support for ISA v2.07 compat level Suraj Jitindar Singh 2016-11-01 4:41 ` Suraj Jitindar Singh 2016-11-01 4:41 ` [PATCH V3 1/2] powerpc: Define new ISA v3.00 logical PVR value and PCR register value Suraj Jitindar Singh 2016-11-01 4:41 ` Suraj Jitindar Singh 2016-11-08 8:21 ` Michael Ellerman 2016-11-08 8:21 ` Michael Ellerman 2016-11-08 23:18 ` Suraj Jitindar Singh 2016-11-08 23:18 ` Suraj Jitindar Singh 2016-11-10 10:36 ` Michael Ellerman 2016-11-10 10:36 ` Michael Ellerman 2016-11-11 6:11 ` Suraj Jitindar Singh [this message] 2016-11-11 6:11 ` Suraj Jitindar Singh 2016-11-01 4:41 ` [PATCH V3 2/2] powerpc/kvm: Update kvmppc_set_arch_compat() for ISA v3.00 Suraj Jitindar Singh 2016-11-01 4:41 ` Suraj Jitindar Singh
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