From: Catalin Marinas <catalin.marinas@arm.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: Marc Zyngier <maz@kernel.org>,
Steven Price <steven.price@arm.com>,
Peter Maydell <peter.maydell@linaro.org>,
Haibo Xu <haibo.xu@linaro.org>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Juan Quintela <quintela@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
arm-mail-list <linux-arm-kernel@lists.infradead.org>,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v5 0/2] MTE support for KVM guest
Date: Wed, 9 Dec 2020 18:39:20 +0000 [thread overview]
Message-ID: <20201209183920.GI13566@gaia> (raw)
In-Reply-To: <8c39b104-39c3-7cca-82b9-2e47d7cb9a9a@linaro.org>
On Wed, Dec 09, 2020 at 12:27:59PM -0600, Richard Henderson wrote:
> On 12/9/20 9:27 AM, Catalin Marinas wrote:
> > On Wed, Dec 09, 2020 at 01:25:18PM +0000, Marc Zyngier wrote:
> >> Would this syscall operate on the guest address space? Or on the VMM's
> >> own mapping?
> ...
> > Whatever is easier for the VMM, I don't think it matters as long as the
> > host kernel can get the actual physical address (and linear map
> > correspondent). Maybe simpler if it's the VMM address space as the
> > kernel can check the access permissions in case you want to hide the
> > guest memory from the VMM for other reasons (migration is also off the
> > table).
>
> Indeed, such a syscall is no longer specific to vmm's and may be used for any
> bulk move of tags that userland might want.
For CRIU, I think the current ptrace interface would do. With VMMs, the
same remote VM model doesn't apply (the "remote" VM is actually the
guest memory). I'd keep this under a KVM ioctl() number rather than a
new, specific syscall.
> > Without syscalls, an option would be for the VMM to create two mappings:
> > one with PROT_MTE for migration and the other without for normal DMA
> > etc. That's achievable using memfd_create() or shm_open() and two mmap()
> > calls, only one having PROT_MTE. The VMM address space should be
> > sufficiently large to map two guest IPAs.
>
> I would have thought that the best way is to use TCO, so that we don't have to
> have dual mappings (and however many MB of extra page tables that might imply).
The problem appears when the VMM wants to use MTE itself (e.g. linked
against an MTE-aware glibc), toggling TCO is no longer generic enough,
especially when it comes to device emulation.
--
Catalin
WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>,
Juan Quintela <quintela@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Marc Zyngier <maz@kernel.org>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Steven Price <steven.price@arm.com>,
arm-mail-list <linux-arm-kernel@lists.infradead.org>,
Haibo Xu <haibo.xu@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v5 0/2] MTE support for KVM guest
Date: Wed, 9 Dec 2020 18:39:20 +0000 [thread overview]
Message-ID: <20201209183920.GI13566@gaia> (raw)
In-Reply-To: <8c39b104-39c3-7cca-82b9-2e47d7cb9a9a@linaro.org>
On Wed, Dec 09, 2020 at 12:27:59PM -0600, Richard Henderson wrote:
> On 12/9/20 9:27 AM, Catalin Marinas wrote:
> > On Wed, Dec 09, 2020 at 01:25:18PM +0000, Marc Zyngier wrote:
> >> Would this syscall operate on the guest address space? Or on the VMM's
> >> own mapping?
> ...
> > Whatever is easier for the VMM, I don't think it matters as long as the
> > host kernel can get the actual physical address (and linear map
> > correspondent). Maybe simpler if it's the VMM address space as the
> > kernel can check the access permissions in case you want to hide the
> > guest memory from the VMM for other reasons (migration is also off the
> > table).
>
> Indeed, such a syscall is no longer specific to vmm's and may be used for any
> bulk move of tags that userland might want.
For CRIU, I think the current ptrace interface would do. With VMMs, the
same remote VM model doesn't apply (the "remote" VM is actually the
guest memory). I'd keep this under a KVM ioctl() number rather than a
new, specific syscall.
> > Without syscalls, an option would be for the VMM to create two mappings:
> > one with PROT_MTE for migration and the other without for normal DMA
> > etc. That's achievable using memfd_create() or shm_open() and two mmap()
> > calls, only one having PROT_MTE. The VMM address space should be
> > sufficiently large to map two guest IPAs.
>
> I would have thought that the best way is to use TCO, so that we don't have to
> have dual mappings (and however many MB of extra page tables that might imply).
The problem appears when the VMM wants to use MTE itself (e.g. linked
against an MTE-aware glibc), toggling TCO is no longer generic enough,
especially when it comes to device emulation.
--
Catalin
WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: Juan Quintela <quintela@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Marc Zyngier <maz@kernel.org>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Steven Price <steven.price@arm.com>,
arm-mail-list <linux-arm-kernel@lists.infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v5 0/2] MTE support for KVM guest
Date: Wed, 9 Dec 2020 18:39:20 +0000 [thread overview]
Message-ID: <20201209183920.GI13566@gaia> (raw)
In-Reply-To: <8c39b104-39c3-7cca-82b9-2e47d7cb9a9a@linaro.org>
On Wed, Dec 09, 2020 at 12:27:59PM -0600, Richard Henderson wrote:
> On 12/9/20 9:27 AM, Catalin Marinas wrote:
> > On Wed, Dec 09, 2020 at 01:25:18PM +0000, Marc Zyngier wrote:
> >> Would this syscall operate on the guest address space? Or on the VMM's
> >> own mapping?
> ...
> > Whatever is easier for the VMM, I don't think it matters as long as the
> > host kernel can get the actual physical address (and linear map
> > correspondent). Maybe simpler if it's the VMM address space as the
> > kernel can check the access permissions in case you want to hide the
> > guest memory from the VMM for other reasons (migration is also off the
> > table).
>
> Indeed, such a syscall is no longer specific to vmm's and may be used for any
> bulk move of tags that userland might want.
For CRIU, I think the current ptrace interface would do. With VMMs, the
same remote VM model doesn't apply (the "remote" VM is actually the
guest memory). I'd keep this under a KVM ioctl() number rather than a
new, specific syscall.
> > Without syscalls, an option would be for the VMM to create two mappings:
> > one with PROT_MTE for migration and the other without for normal DMA
> > etc. That's achievable using memfd_create() or shm_open() and two mmap()
> > calls, only one having PROT_MTE. The VMM address space should be
> > sufficiently large to map two guest IPAs.
>
> I would have thought that the best way is to use TCO, so that we don't have to
> have dual mappings (and however many MB of extra page tables that might imply).
The problem appears when the VMM wants to use MTE itself (e.g. linked
against an MTE-aware glibc), toggling TCO is no longer generic enough,
especially when it comes to device emulation.
--
Catalin
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>,
Juan Quintela <quintela@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Marc Zyngier <maz@kernel.org>,
lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
Steven Price <steven.price@arm.com>,
arm-mail-list <linux-arm-kernel@lists.infradead.org>,
Haibo Xu <haibo.xu@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v5 0/2] MTE support for KVM guest
Date: Wed, 9 Dec 2020 18:39:20 +0000 [thread overview]
Message-ID: <20201209183920.GI13566@gaia> (raw)
In-Reply-To: <8c39b104-39c3-7cca-82b9-2e47d7cb9a9a@linaro.org>
On Wed, Dec 09, 2020 at 12:27:59PM -0600, Richard Henderson wrote:
> On 12/9/20 9:27 AM, Catalin Marinas wrote:
> > On Wed, Dec 09, 2020 at 01:25:18PM +0000, Marc Zyngier wrote:
> >> Would this syscall operate on the guest address space? Or on the VMM's
> >> own mapping?
> ...
> > Whatever is easier for the VMM, I don't think it matters as long as the
> > host kernel can get the actual physical address (and linear map
> > correspondent). Maybe simpler if it's the VMM address space as the
> > kernel can check the access permissions in case you want to hide the
> > guest memory from the VMM for other reasons (migration is also off the
> > table).
>
> Indeed, such a syscall is no longer specific to vmm's and may be used for any
> bulk move of tags that userland might want.
For CRIU, I think the current ptrace interface would do. With VMMs, the
same remote VM model doesn't apply (the "remote" VM is actually the
guest memory). I'd keep this under a KVM ioctl() number rather than a
new, specific syscall.
> > Without syscalls, an option would be for the VMM to create two mappings:
> > one with PROT_MTE for migration and the other without for normal DMA
> > etc. That's achievable using memfd_create() or shm_open() and two mmap()
> > calls, only one having PROT_MTE. The VMM address space should be
> > sufficiently large to map two guest IPAs.
>
> I would have thought that the best way is to use TCO, so that we don't have to
> have dual mappings (and however many MB of extra page tables that might imply).
The problem appears when the VMM wants to use MTE itself (e.g. linked
against an MTE-aware glibc), toggling TCO is no longer generic enough,
especially when it comes to device emulation.
--
Catalin
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-12-09 18:40 UTC|newest]
Thread overview: 152+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 15:38 [PATCH v5 0/2] MTE support for KVM guest Steven Price
2020-11-19 15:38 ` Steven Price
2020-11-19 15:38 ` Steven Price
2020-11-19 15:38 ` Steven Price
2020-11-19 15:39 ` [PATCH v5 1/2] arm64: kvm: Save/restore MTE registers Steven Price
2020-11-19 15:39 ` Steven Price
2020-11-19 15:39 ` Steven Price
2020-11-19 15:39 ` Steven Price
2020-11-19 15:39 ` [PATCH v5 2/2] arm64: kvm: Introduce MTE VCPU feature Steven Price
2020-11-19 15:39 ` Steven Price
2020-11-19 15:39 ` Steven Price
2020-11-19 15:39 ` Steven Price
2020-11-19 15:45 ` [PATCH v5 0/2] MTE support for KVM guest Peter Maydell
2020-11-19 15:45 ` Peter Maydell
2020-11-19 15:45 ` Peter Maydell
2020-11-19 15:45 ` Peter Maydell
2020-11-19 15:57 ` Steven Price
2020-11-19 15:57 ` Steven Price
2020-11-19 15:57 ` Steven Price
2020-11-19 15:57 ` Steven Price
2020-11-19 16:39 ` Peter Maydell
2020-11-19 16:39 ` Peter Maydell
2020-11-19 16:39 ` Peter Maydell
2020-11-19 16:39 ` Peter Maydell
2020-11-19 18:42 ` Andrew Jones
2020-11-19 18:42 ` Andrew Jones
2020-11-19 18:42 ` Andrew Jones
2020-11-19 18:42 ` Andrew Jones
2020-11-19 19:11 ` Marc Zyngier
2020-11-19 19:11 ` Marc Zyngier
2020-11-19 19:11 ` Marc Zyngier
2020-11-19 19:11 ` Marc Zyngier
2020-11-20 9:50 ` Steven Price
2020-11-20 9:50 ` Steven Price
2020-11-20 9:50 ` Steven Price
2020-11-20 9:50 ` Steven Price
2020-11-20 9:56 ` Marc Zyngier
2020-11-20 9:56 ` Marc Zyngier
2020-11-20 9:56 ` Marc Zyngier
2020-11-20 9:56 ` Marc Zyngier
2020-11-20 9:58 ` Steven Price
2020-11-20 9:58 ` Steven Price
2020-11-20 9:58 ` Steven Price
2020-11-20 9:58 ` Steven Price
2020-12-04 8:25 ` Haibo Xu
2020-12-04 8:25 ` Haibo Xu
2020-12-04 8:25 ` Haibo Xu
2020-12-04 8:25 ` Haibo Xu
2020-12-07 14:48 ` Steven Price
2020-12-07 14:48 ` Steven Price
2020-12-07 14:48 ` Steven Price
2020-12-07 14:48 ` Steven Price
2020-12-07 15:27 ` Peter Maydell
2020-12-07 15:27 ` Peter Maydell
2020-12-07 15:27 ` Peter Maydell
2020-12-07 15:27 ` Peter Maydell
2020-12-07 15:45 ` Steven Price
2020-12-07 15:45 ` Steven Price
2020-12-07 15:45 ` Steven Price
2020-12-07 15:45 ` Steven Price
2020-12-07 16:05 ` Marc Zyngier
2020-12-07 16:05 ` Marc Zyngier
2020-12-07 16:05 ` Marc Zyngier
2020-12-07 16:05 ` Marc Zyngier
2020-12-07 16:34 ` Catalin Marinas
2020-12-07 16:34 ` Catalin Marinas
2020-12-07 16:34 ` Catalin Marinas
2020-12-07 16:34 ` Catalin Marinas
2020-12-07 19:03 ` Marc Zyngier
2020-12-07 19:03 ` Marc Zyngier
2020-12-07 19:03 ` Marc Zyngier
2020-12-07 19:03 ` Marc Zyngier
2020-12-08 17:21 ` Catalin Marinas
2020-12-08 17:21 ` Catalin Marinas
2020-12-08 17:21 ` Catalin Marinas
2020-12-08 17:21 ` Catalin Marinas
2020-12-08 18:21 ` Marc Zyngier
2020-12-08 18:21 ` Marc Zyngier
2020-12-08 18:21 ` Marc Zyngier
2020-12-08 18:21 ` Marc Zyngier
2020-12-09 12:44 ` Catalin Marinas
2020-12-09 12:44 ` Catalin Marinas
2020-12-09 12:44 ` Catalin Marinas
2020-12-09 12:44 ` Catalin Marinas
2020-12-09 13:25 ` Marc Zyngier
2020-12-09 13:25 ` Marc Zyngier
2020-12-09 13:25 ` Marc Zyngier
2020-12-09 13:25 ` Marc Zyngier
2020-12-09 15:27 ` Catalin Marinas
2020-12-09 15:27 ` Catalin Marinas
2020-12-09 15:27 ` Catalin Marinas
2020-12-09 15:27 ` Catalin Marinas
2020-12-09 18:27 ` Richard Henderson
2020-12-09 18:27 ` Richard Henderson
2020-12-09 18:27 ` Richard Henderson
2020-12-09 18:27 ` Richard Henderson
2020-12-09 18:39 ` Catalin Marinas [this message]
2020-12-09 18:39 ` Catalin Marinas
2020-12-09 18:39 ` Catalin Marinas
2020-12-09 18:39 ` Catalin Marinas
2020-12-09 20:13 ` Richard Henderson
2020-12-09 20:13 ` Richard Henderson
2020-12-09 20:13 ` Richard Henderson
2020-12-09 20:13 ` Richard Henderson
2020-12-09 20:20 ` Peter Maydell
2020-12-09 20:20 ` Peter Maydell
2020-12-09 20:20 ` Peter Maydell
2020-12-09 20:20 ` Peter Maydell
2020-12-07 16:44 ` Dr. David Alan Gilbert
2020-12-07 16:44 ` Dr. David Alan Gilbert
2020-12-07 16:44 ` Dr. David Alan Gilbert
2020-12-07 16:44 ` Dr. David Alan Gilbert
2020-12-07 17:10 ` Peter Maydell
2020-12-07 17:10 ` Peter Maydell
2020-12-07 17:10 ` Peter Maydell
2020-12-07 17:10 ` Peter Maydell
2020-12-07 17:44 ` Dr. David Alan Gilbert
2020-12-07 17:44 ` Dr. David Alan Gilbert
2020-12-07 17:44 ` Dr. David Alan Gilbert
2020-12-07 17:44 ` Dr. David Alan Gilbert
2020-12-08 10:05 ` Haibo Xu
2020-12-08 10:05 ` Haibo Xu
2020-12-08 10:05 ` Haibo Xu
2020-12-08 10:05 ` Haibo Xu
2020-12-08 9:51 ` Haibo Xu
2020-12-08 9:51 ` Haibo Xu
2020-12-08 9:51 ` Haibo Xu
2020-12-08 9:51 ` Haibo Xu
2020-12-08 10:01 ` Marc Zyngier
2020-12-08 10:01 ` Marc Zyngier
2020-12-08 10:01 ` Marc Zyngier
2020-12-08 10:01 ` Marc Zyngier
2020-12-08 10:10 ` Haibo Xu
2020-12-08 10:10 ` Haibo Xu
2020-12-08 10:10 ` Haibo Xu
2020-12-08 10:10 ` Haibo Xu
2020-12-16 7:31 ` Haibo Xu
2020-12-16 7:31 ` Haibo Xu
2020-12-16 7:31 ` Haibo Xu
2020-12-16 7:31 ` Haibo Xu
2020-12-16 10:22 ` Steven Price
2020-12-16 10:22 ` Steven Price
2020-12-16 10:22 ` Steven Price
2020-12-16 10:22 ` Steven Price
2020-12-17 1:47 ` Haibo Xu
2020-12-17 1:47 ` Haibo Xu
2020-12-17 1:47 ` Haibo Xu
2020-12-17 1:47 ` Haibo Xu
2020-11-23 12:16 ` Dr. David Alan Gilbert
2020-11-23 12:16 ` Dr. David Alan Gilbert
2020-11-23 12:16 ` Dr. David Alan Gilbert
2020-11-23 12:16 ` Dr. David Alan Gilbert
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