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Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested
From: |
Nicolin Chen |
Subject: |
Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device |
Date: |
Thu, 28 Nov 2024 10:22:02 -0800 |
On Thu, Nov 28, 2024 at 08:54:26AM -0400, Jason Gunthorpe wrote:
> On Wed, Nov 27, 2024 at 08:44:47PM -0800, Nicolin Chen wrote:
> > On Wed, Nov 27, 2024 at 11:29:06PM -0500, Donald Dutile wrote:
> > > On 11/27/24 5:21 AM, Shameerali Kolothum Thodi wrote:
> > > > > > W.r.t naming, maybe something related to "hardware-accelerated"?
> > > > > >
> > > > > Given that 'accel' has been used for hw-acceleration elsewhere, that
> > > > > seems
> > > > > like a reasonable 'mode'.
> > > > > But, it needs a paramater to state was is being accelerated.
> > > > > i.e., the more global 'accel=kvm' has 'kvm'.
> > > >
> > > > I was thinking more like calling this hw accelerated nested SMMUv3
> > > > emulation
> > > > as 'smmuv3-accel'. This avoids confusion with the already existing
> > > > 'iommu=smmuv3' that also has a nested emulation support.
> > > >
> > > > ie,
> > > > -device arm-smmuv3-accel,id=smmuv1,bus=pcie.1 \
> > > >
> > ..
> > > I -think- you are saying below, that we have to think a bit more about
> > > this
> > > device tagging. I'm thinking more like
> > > - device arm-smmuv3,accel=<vcmdq>,id=smmu1,bus=pcie.1 \
> >
> > I wonder if we really need a "vcmdq" enabling/disabling option?
> >
> > Jason's suggested approach for a vIOMMU allocation is to retry-
> > on-failure, so my draft patches allocate a TEGRA241_CMDQV type
> > of vIOMMU first, and then fall back to a regular SMMUV3 type if
> > it fails. So, a host that doesn't have a VCMDQ capability could
> > still work with the fallback/default pathway.
>
> It needs to be configurable so the VM can be configured in a
> consistent way across nodes
>
> autodetection of host features is nice for experimenting but scale
> deployments should precisely specify every detail about the VM and not
> rely on host detection. Otherwise the VM instance type will be ill
> defined..
In that case, we'd need to expose a vcmdq capability somewhere.
We do for vIOMMU via hw_info. Should we keep the consistency?
Otherwise, some sysfs nodes (easier for libvirt) could do the
job too: num_available_vintfs, max_vcmdqs_per_vintf, and etc.
Thanks
Nicolin
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, (continued)
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Zhangfei Gao, 2024/11/27
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Eric Auger, 2024/11/28
- RE: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Shameerali Kolothum Thodi, 2024/11/28
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Eric Auger, 2024/11/28
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Jason Gunthorpe, 2024/11/28
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Donald Dutile, 2024/11/27
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Jason Gunthorpe, 2024/11/28
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Donald Dutile, 2024/11/27
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Nicolin Chen, 2024/11/27
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Jason Gunthorpe, 2024/11/28
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device,
Nicolin Chen <=
- RE: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Shameerali Kolothum Thodi, 2024/11/28
- RE: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Shameerali Kolothum Thodi, 2024/11/14
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Eric Auger, 2024/11/14
- RE: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Shameerali Kolothum Thodi, 2024/11/14
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Nicolin Chen, 2024/11/15
- Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device, Eric Auger, 2024/11/13
- [RFC PATCH 3/5] hw/arm/smmuv3: Associate a pci bus with a SMMUv3 Nested device, Shameer Kolothum, 2024/11/08
- [RFC PATCH 4/5] hw/arm/virt-acpi-build: Build IORT with multiple SMMU nodes, Shameer Kolothum, 2024/11/08