From: Paul Mackerras <paulus@ozlabs.org>
To: "Cédric Le Goater" <clg@kaod.org>
Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH 18/19] KVM: PPC: Book3S HV: add passthrough support
Date: Tue, 29 Jan 2019 13:45:03 +1100 [thread overview]
Message-ID: <20190129024503.GA11368@blackberry> (raw)
In-Reply-To: <38b0244d-beb6-3aee-c638-279ca570633c@kaod.org>
On Mon, Jan 28, 2019 at 07:26:00PM +0100, Cédric Le Goater wrote:
> On 1/28/19 7:13 AM, Paul Mackerras wrote:
> > Would we end up with too many VMAs if we just used mmap() to
> > change the mappings from the software-generated pages to the
> > hardware-generated interrupt pages?
> The sPAPR IRQ number space is 0x8000 wide now. The first 4K are
> dedicated to CPU IPIs and the remaining 4K are for devices. We can
Confused. You say the number space has 32768 entries but then imply
there are only 8K entries. Do you mean that the API allows for 15-bit
IRQ numbers but we are only making using of 8192 of them?
> extend the last range if needed as these are for MSIs. Dynamic
> extensions under KVM should work also.
>
> This to say that we have with 8K x 2 (trigger+EOI) pages. This is a
> lot of mmap(), too much. Also the KVM model needs to be compatible
I wasn't suggesting an mmap per IRQ, I meant that the bulk of the
space would be covered by a single mmap, overlaid by subsequent mmaps
where we need to map real device interrupts.
> with the QEMU emulated one and it was simpler to have one overall
> memory region for the IPI ESBs, one for the END ESBs (if we support
> that one day) and one for the TIMA.
>
> > Are the necessary pages for a PCI
> > passthrough device contiguous in both host real space
>
> They should as they are the PHB4 ESBs.
>
> > and guest real space ?
>
> also. That's how we organized the mapping.
"How we organized the mapping" is a significant design decision that I
haven't seen documented anywhere, and is really needed for
understanding what's going on.
>
> > If so we'd only need one mmap() for all the device's interrupt
> > pages.
>
> Ah. So we would want to make a special case for the passthrough
> device and have a mmap() and a memory region for its ESBs. Hmm.
>
> Wouldn't that require to hot plug a memory region under the guest ?
No; the way that a memory region works is that userspace can do
whatever disparate mappings it likes within the region on the user
process side, and the corresponding region of guest real address space
follows that automatically.
> which means that we need to provision an address space/container
> region for theses regions. What are the benefits ?
>
> Is clearing the PTEs and repopulating the VMA unsafe ?
Explicitly unmapping parts of the VMA seems like the wrong way to do
it. If you have a device mmap where the device wants to change the
physical page underlying parts of the mapping, there should be a way
for it to do that explicitly (but I don't know off the top of my head
what the interface to do that is).
However, I still haven't seen a clear and concise explanation of what
is being changed, when, and why we need to do that.
Paul.
next prev parent reply other threads:[~2019-01-29 2:46 UTC|newest]
Thread overview: 135+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-07 18:43 [PATCH 00/19] KVM: PPC: Book3S HV: add XIVE native exploitation mode Cédric Le Goater
2019-01-07 18:43 ` [PATCH 01/19] powerpc/xive: export flags for the XIVE native exploitation mode hcalls Cédric Le Goater
2019-01-09 3:33 ` David Gibson
2019-01-09 13:08 ` Michael Ellerman
2019-01-09 13:38 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 02/19] powerpc/xive: add OPAL extensions for the XIVE native exploitation support Cédric Le Goater
2019-01-09 4:26 ` David Gibson
2019-01-07 18:43 ` [PATCH 03/19] KVM: PPC: Book3S HV: check the IRQ controller type Cédric Le Goater
2019-01-09 4:27 ` David Gibson
2019-01-22 4:56 ` Paul Mackerras
2019-01-23 16:24 ` Cédric Le Goater
2019-02-04 0:50 ` David Gibson
2019-02-04 10:16 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 04/19] KVM: PPC: Book3S HV: export services for the XIVE native exploitation device Cédric Le Goater
2019-01-11 4:09 ` David Gibson
2019-01-07 18:43 ` [PATCH 05/19] KVM: PPC: Book3S HV: add a new KVM device for the XIVE native exploitation mode Cédric Le Goater
2019-01-22 5:05 ` Paul Mackerras
2019-01-23 16:28 ` Cédric Le Goater
2019-01-28 17:35 ` Cédric Le Goater
2019-01-30 4:29 ` Paul Mackerras
2019-01-30 7:01 ` Cédric Le Goater
2019-01-31 3:01 ` Paul Mackerras
2019-02-01 17:03 ` Cédric Le Goater
2019-02-04 4:25 ` David Gibson
2019-02-04 11:19 ` Cédric Le Goater
2019-02-05 5:26 ` David Gibson
2019-01-07 18:43 ` [PATCH 06/19] KVM: PPC: Book3S HV: add a GET_ESB_FD control to the XIVE native device Cédric Le Goater
2019-01-22 5:09 ` Paul Mackerras
2019-01-23 16:48 ` Cédric Le Goater
2019-02-04 4:45 ` David Gibson
2019-02-04 11:30 ` Cédric Le Goater
2019-02-05 5:28 ` David Gibson
2019-02-05 12:55 ` Cédric Le Goater
2019-02-06 1:23 ` David Gibson
2019-02-06 7:21 ` Cédric Le Goater
2019-02-07 2:49 ` David Gibson
2019-02-07 9:03 ` Cédric Le Goater
2019-02-08 5:15 ` David Gibson
2019-02-08 7:58 ` Cédric Le Goater
2019-02-08 21:53 ` Paul Mackerras
2019-02-09 9:41 ` Cédric Le Goater
2019-02-11 2:38 ` David Gibson
2019-02-11 6:42 ` Benjamin Herrenschmidt
2019-02-12 22:07 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 07/19] KVM: PPC: Book3S HV: add a GET_TIMA_FD control to " Cédric Le Goater
2019-01-07 18:43 ` [PATCH 08/19] KVM: PPC: Book3S HV: add a VC_BASE control to the " Cédric Le Goater
2019-01-22 5:14 ` Paul Mackerras
2019-01-23 16:56 ` Cédric Le Goater
2019-02-04 4:49 ` David Gibson
2019-02-04 15:36 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 09/19] KVM: PPC: Book3S HV: add a SET_SOURCE " Cédric Le Goater
2019-02-04 4:57 ` David Gibson
2019-02-04 19:07 ` Cédric Le Goater
2019-02-05 5:35 ` David Gibson
2019-02-05 13:39 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 10/19] KVM: PPC: Book3S HV: add a EISN attribute to kvmppc_xive_irq_state Cédric Le Goater
2019-01-07 18:43 ` [PATCH 11/19] KVM: PPC: Book3S HV: add support for the XIVE native exploitation mode hcalls Cédric Le Goater
2019-01-22 5:23 ` Paul Mackerras
2019-01-23 6:44 ` Benjamin Herrenschmidt
2019-01-23 8:48 ` Cédric Le Goater
2019-01-23 10:26 ` Paul Mackerras
2019-01-23 10:48 ` Cédric Le Goater
2019-01-23 21:23 ` Benjamin Herrenschmidt
2019-01-07 18:43 ` [PATCH 12/19] KVM: PPC: Book3S HV: record guest queue page address Cédric Le Goater
2019-02-04 5:15 ` David Gibson
2019-02-04 15:37 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 13/19] KVM: PPC: Book3S HV: add a SYNC control for the XIVE native migration Cédric Le Goater
2019-02-04 5:17 ` David Gibson
2019-02-04 15:39 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 14/19] KVM: PPC: Book3S HV: add a control to make the XIVE EQ pages dirty Cédric Le Goater
2019-02-04 5:18 ` David Gibson
2019-02-04 15:46 ` Cédric Le Goater
2019-02-05 5:30 ` David Gibson
2019-01-07 18:43 ` [PATCH 15/19] KVM: PPC: Book3S HV: add get/set accessors for the source configuration Cédric Le Goater
2019-02-04 5:21 ` David Gibson
2019-02-04 16:07 ` Cédric Le Goater
2019-02-05 5:32 ` David Gibson
2019-02-05 13:03 ` Cédric Le Goater
2019-02-06 1:23 ` David Gibson
2019-02-06 1:24 ` David Gibson
2019-02-06 7:07 ` Cédric Le Goater
2019-02-07 2:48 ` David Gibson
2019-02-07 9:13 ` Cédric Le Goater
2019-02-08 5:15 ` David Gibson
2019-02-14 16:50 ` Cédric Le Goater
2019-01-07 18:43 ` [PATCH 16/19] KVM: PPC: Book3S HV: add get/set accessors for the EQ configuration Cédric Le Goater
2019-02-04 5:24 ` David Gibson
2019-02-05 17:45 ` Cédric Le Goater
2019-01-07 19:10 ` [PATCH 17/19] KVM: PPC: Book3S HV: add get/set accessors for the VP XIVE state Cédric Le Goater
2019-01-07 19:10 ` [PATCH 18/19] KVM: PPC: Book3S HV: add passthrough support Cédric Le Goater
2019-01-22 5:26 ` Paul Mackerras
2019-01-23 6:45 ` Benjamin Herrenschmidt
2019-01-23 10:30 ` Paul Mackerras
2019-01-23 11:07 ` Cédric Le Goater
2019-01-28 6:13 ` Paul Mackerras
2019-01-28 18:26 ` Cédric Le Goater
2019-01-29 2:45 ` Paul Mackerras [this message]
2019-01-29 13:47 ` Cédric Le Goater
2019-01-30 6:20 ` Paul Mackerras
2019-01-30 15:54 ` Cédric Le Goater
2019-01-31 2:48 ` Paul Mackerras
2019-01-29 4:12 ` Paul Mackerras
2019-01-29 17:44 ` Cédric Le Goater
2019-01-30 5:55 ` Paul Mackerras
2019-01-30 7:06 ` Cédric Le Goater
2019-01-23 21:25 ` Benjamin Herrenschmidt
2019-01-24 8:41 ` Cédric Le Goater
2019-01-28 4:43 ` Paul Mackerras
2019-01-29 13:46 ` Cédric Le Goater
2019-01-07 19:10 ` [PATCH 19/19] KVM: introduce a KVM_DELETE_DEVICE ioctl Cédric Le Goater
2019-01-22 5:42 ` Paul Mackerras
2019-01-23 18:39 ` Cédric Le Goater
2019-01-23 21:32 ` Benjamin Herrenschmidt
2019-02-04 5:26 ` [PATCH 17/19] KVM: PPC: Book3S HV: add get/set accessors for the VP XIVE state David Gibson
2019-02-04 18:57 ` Cédric Le Goater
2019-02-05 5:33 ` David Gibson
2019-02-05 11:58 ` Cédric Le Goater
2019-02-06 1:19 ` David Gibson
2019-01-22 4:46 ` [PATCH 00/19] KVM: PPC: Book3S HV: add XIVE native exploitation mode Paul Mackerras
2019-01-23 19:07 ` Cédric Le Goater
2019-01-23 21:35 ` Benjamin Herrenschmidt
2019-01-26 8:25 ` Cédric Le Goater
2019-02-04 5:36 ` David Gibson
2019-02-05 11:31 ` Cédric Le Goater
2019-02-05 22:13 ` Paul Mackerras
2019-02-06 1:18 ` David Gibson
2019-02-06 7:35 ` Cédric Le Goater
2019-02-07 2:51 ` David Gibson
2019-02-07 8:31 ` Cédric Le Goater
2019-02-08 5:07 ` David Gibson
2019-02-08 7:38 ` Cédric Le Goater
2019-01-28 5:51 ` Paul Mackerras
2019-01-29 13:51 ` Cédric Le Goater
2019-01-30 5:40 ` Paul Mackerras
2019-01-30 15:36 ` Cédric Le Goater
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