From: Alexander Graf <agraf@suse.de>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Mihai Caraman <mihai.caraman@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] KVM: PPC: Bookehv: Get vcpu's last instruction for emulation
Date: Fri, 02 May 2014 13:10:51 +0200 [thread overview]
Message-ID: <53637D3B.4010205@suse.de> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D0F705051@AcuExch.aculab.com>
On 05/02/2014 12:12 PM, David Laight wrote:
> From: Alexander Graf
> ...
>>> + page = pfn_to_page(pfn);
>>> + eaddr = (unsigned long)kmap_atomic(page);
>>> + eaddr |= addr & ~PAGE_MASK;
>>> + *instr = *(u32 *)eaddr;
>>> + kunmap_atomic((u32 *)eaddr);
>> I think I'd rather write this as
>>
>> *instr = *(u32 *)(eaddr | (addr & ~PAGE));
>> kunmap_atomic((void*)eaddr);
>>
>> to make sure we pass the unmap function the same value we got from the
>> map function.
>>
>> Otherwise looks good to me.
> Is there any mileage in keeping a virtual address page allocated (per cpu)
> for this (and similar) accesses to physical memory?
> Not having to search for a free VA page might speed things up (if that matters).
I like the idea, though I'm not sure how that would best fit into the
current memory mapping ecosystem.
> You also probably want the page mapped uncached - no point polluting the data
> cache.
Do e500 chips have a shared I/D cache somewhere? If they do, that
particular instruction would already be there, so no pollution but nice
performance.
Alex
WARNING: multiple messages have this Message-ID (diff)
From: Alexander Graf <agraf@suse.de>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Mihai Caraman <mihai.caraman@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] KVM: PPC: Bookehv: Get vcpu's last instruction for emulation
Date: Fri, 02 May 2014 13:10:51 +0200 [thread overview]
Message-ID: <53637D3B.4010205@suse.de> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D0F705051@AcuExch.aculab.com>
On 05/02/2014 12:12 PM, David Laight wrote:
> From: Alexander Graf
> ...
>>> + page = pfn_to_page(pfn);
>>> + eaddr = (unsigned long)kmap_atomic(page);
>>> + eaddr |= addr & ~PAGE_MASK;
>>> + *instr = *(u32 *)eaddr;
>>> + kunmap_atomic((u32 *)eaddr);
>> I think I'd rather write this as
>>
>> *instr = *(u32 *)(eaddr | (addr & ~PAGE));
>> kunmap_atomic((void*)eaddr);
>>
>> to make sure we pass the unmap function the same value we got from the
>> map function.
>>
>> Otherwise looks good to me.
> Is there any mileage in keeping a virtual address page allocated (per cpu)
> for this (and similar) accesses to physical memory?
> Not having to search for a free VA page might speed things up (if that matters).
I like the idea, though I'm not sure how that would best fit into the
current memory mapping ecosystem.
> You also probably want the page mapped uncached - no point polluting the data
> cache.
Do e500 chips have a shared I/D cache somewhere? If they do, that
particular instruction would already be there, so no pollution but nice
performance.
Alex
WARNING: multiple messages have this Message-ID (diff)
From: Alexander Graf <agraf@suse.de>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Mihai Caraman <mihai.caraman@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] KVM: PPC: Bookehv: Get vcpu's last instruction for emulation
Date: Fri, 02 May 2014 11:10:51 +0000 [thread overview]
Message-ID: <53637D3B.4010205@suse.de> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D0F705051@AcuExch.aculab.com>
On 05/02/2014 12:12 PM, David Laight wrote:
> From: Alexander Graf
> ...
>>> + page = pfn_to_page(pfn);
>>> + eaddr = (unsigned long)kmap_atomic(page);
>>> + eaddr |= addr & ~PAGE_MASK;
>>> + *instr = *(u32 *)eaddr;
>>> + kunmap_atomic((u32 *)eaddr);
>> I think I'd rather write this as
>>
>> *instr = *(u32 *)(eaddr | (addr & ~PAGE));
>> kunmap_atomic((void*)eaddr);
>>
>> to make sure we pass the unmap function the same value we got from the
>> map function.
>>
>> Otherwise looks good to me.
> Is there any mileage in keeping a virtual address page allocated (per cpu)
> for this (and similar) accesses to physical memory?
> Not having to search for a free VA page might speed things up (if that matters).
I like the idea, though I'm not sure how that would best fit into the
current memory mapping ecosystem.
> You also probably want the page mapped uncached - no point polluting the data
> cache.
Do e500 chips have a shared I/D cache somewhere? If they do, that
particular instruction would already be there, so no pollution but nice
performance.
Alex
next prev parent reply other threads:[~2014-05-02 11:10 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-01 0:45 [PATCH v2 0/4] KVM: PPC: Read guest instruction from kvmppc_get_last_inst() Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-01 0:45 ` [PATCH v2 1/4] KVM: PPC: e500mc: Revert "add load inst fixup" Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-02 9:24 ` Alexander Graf
2014-05-02 9:24 ` Alexander Graf
2014-05-02 9:24 ` Alexander Graf
2014-05-02 23:14 ` mihai.caraman
2014-05-02 23:14 ` mihai.caraman
2014-05-02 23:14 ` mihai.caraman
2014-05-03 22:14 ` Alexander Graf
2014-05-03 22:14 ` Alexander Graf
2014-05-03 22:14 ` Alexander Graf
2014-05-06 15:48 ` mihai.caraman
2014-05-06 15:48 ` mihai.caraman
2014-05-06 15:48 ` mihai.caraman
2014-05-06 15:54 ` Alexander Graf
2014-05-06 15:54 ` Alexander Graf
2014-05-06 15:54 ` Alexander Graf
2014-05-01 0:45 ` [PATCH v2 2/4] KVM: PPC: Book3e: Add TLBSEL/TSIZE defines for MAS0/1 Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-01 0:45 ` [PATCH v2 3/4] KVM: PPC: Alow kvmppc_get_last_inst() to fail Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-02 9:54 ` Alexander Graf
2014-05-02 9:54 ` Alexander Graf
2014-05-02 9:54 ` Alexander Graf
2014-05-06 19:06 ` mihai.caraman
2014-05-06 19:06 ` mihai.caraman
2014-05-06 19:06 ` mihai.caraman
2014-05-08 13:31 ` Alexander Graf
2014-05-08 13:31 ` Alexander Graf
2014-05-08 13:31 ` Alexander Graf
2014-05-01 0:45 ` [PATCH v2 4/4] KVM: PPC: Bookehv: Get vcpu's last instruction for emulation Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-01 0:45 ` Mihai Caraman
2014-05-02 10:01 ` Alexander Graf
2014-05-02 10:01 ` Alexander Graf
2014-05-02 10:01 ` Alexander Graf
2014-05-02 10:12 ` David Laight
2014-05-02 10:12 ` David Laight
2014-05-02 10:12 ` David Laight
2014-05-02 11:10 ` Alexander Graf [this message]
2014-05-02 11:10 ` Alexander Graf
2014-05-02 11:10 ` Alexander Graf
2014-05-02 15:32 ` Scott Wood
2014-05-02 15:32 ` Scott Wood
2014-05-02 15:32 ` Scott Wood
-- strict thread matches above, loose matches on Subject: below --
2014-05-01 0:39 [PATCH v2 0/4] KVM: PPC: Read guest instruction from kvmppc_get_last_inst() Mihai Caraman
2014-05-01 0:39 ` Mihai Caraman
2014-05-01 0:39 ` Mihai Caraman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=53637D3B.4010205@suse.de \
--to=agraf@suse.de \
--cc=David.Laight@ACULAB.COM \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mihai.caraman@freescale.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.