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From: Peter Maydell <peter.maydell@linaro.org>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: arm-mail-list <linux-arm-kernel@lists.infradead.org>,
	kvmarm@lists.cs.columbia.edu, kvm-devel <kvm@vger.kernel.org>,
	"Marc Zyngier" <marc.zyngier@arm.com>,
	"Christoffer Dall" <cdall@kernel.org>,
	"Eric Auger" <eric.auger@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Will Deacon" <will.deacon@arm.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"James Morse" <james.morse@arm.com>,
	"Dave P Martin" <dave.martin@arm.com>,
	julien.grall@arm.com,
	"lkml - Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 18/18] kvm: arm64: Allow tuning the physical address size for VM
Date: Tue, 18 Sep 2018 02:55:05 +0100	[thread overview]
Message-ID: <CAFEAcA8eWYkzwFYHyP49dasK-NDVbbm=6DbEFNNPq9ZAdUM7JQ@mail.gmail.com> (raw)
In-Reply-To: <20180917104144.19188-19-suzuki.poulose@arm.com>

On 17 September 2018 at 11:41, Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -122,6 +122,14 @@ the default trap & emulate implementation (which changes the virtual
>  memory layout to fit in user mode), check KVM_CAP_MIPS_VZ and use the
>  flag KVM_VM_MIPS_VZ.
>
> +To configure the physical address space size for a VM (IPA size) on arm64,
> +check KVM_CAP_ARM_VM_PHYS_SHIFT (which returns the maximum limit for the
> +IPA shift) and use KVM_VM_TYPE_ARM_PHYS_SHIFT(PHYS_SHIFT). Bits[7-0] of the
> +machine type has been reserved for specifying the PHYS_SHIFT.
> +The supported range is [32...IPA_LIMIT], where IPA_LIMIT could be
> +identified by checking KVM_CAP_ARM_VM_PHYS_SHIFT. For backward compatibility
> +a value of 0 selects 40bits.
> +

Given this as the API documentation, I don't think I could figure out
what I as a userspace user of it need to do without looking at the
kernel code. Could I ask you to expand it so that it is a bit less
terse and a bit more detailed? (For instance, what is a PHYS_SHIFT
and why do I have to specify it rather than just telling the kernel
I want a 48 bit guest address space?)

thanks
-- PMM

  parent reply	other threads:[~2018-09-18  1:55 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-17 10:41 [PATCH v5 00/18] kvm: arm64: Dynamic IPA and 52bit IPA Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 01/18] kvm: arm/arm64: Fix stage2_flush_memslot for 4 level page table Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 02/18] kvm: arm/arm64: Remove spurious WARN_ON Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 03/18] kvm: arm64: Add helper for loading the stage2 setting for a VM Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 04/18] arm64: Add a helper for PARange to physical shift conversion Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 05/18] kvm: arm64: Clean up VTCR_EL2 initialisation Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 06/18] kvm: arm/arm64: Allow arch specific configurations for VM Suzuki K Poulose
2018-09-20 10:22   ` Auger Eric
2018-09-17 10:41 ` [PATCH v5 07/18] kvm: arm64: Configure VTCR_EL2 per VM Suzuki K Poulose
2018-09-20 10:21   ` Auger Eric
2018-09-20 10:38     ` Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 08/18] kvm: arm/arm64: Prepare for VM specific stage2 translations Suzuki K Poulose
2018-09-20 14:07   ` Auger Eric
2018-09-17 10:41 ` [PATCH v5 09/18] kvm: arm64: Prepare for dynamic stage2 page table layout Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 10/18] kvm: arm64: Make stage2 page table layout dynamic Suzuki K Poulose
2018-09-20 14:07   ` Auger Eric
2018-09-17 10:41 ` [PATCH v5 11/18] kvm: arm64: Dynamic configuration of VTTBR mask Suzuki K Poulose
2018-09-20 14:07   ` Auger Eric
2018-09-20 15:22     ` Suzuki K Poulose
2018-09-25 11:56       ` Auger Eric
2018-09-17 10:41 ` [PATCH v5 12/18] kvm: arm64: Configure VTCR_EL2.SL0 per VM Suzuki K Poulose
2018-09-20 14:25   ` Auger Eric
2018-09-20 15:25     ` Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 13/18] kvm: arm64: Switch to per VM IPA limit Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 14/18] vgic: Add support for 52bit guest physical address Suzuki K Poulose
2018-09-21 14:57   ` Auger Eric
2018-09-25 10:49     ` Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 15/18] kvm: arm64: Add 52bit support for PAR to HPFAR conversoin Suzuki K Poulose
2018-09-25  9:59   ` Auger Eric
2018-09-17 10:41 ` [PATCH v5 16/18] kvm: arm64: Set a limit on the IPA size Suzuki K Poulose
2018-09-25  9:59   ` Auger Eric
2018-09-25 11:10     ` Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 17/18] kvm: arm64: Limit the minimum number of page table levels Suzuki K Poulose
2018-09-25 10:00   ` Auger Eric
2018-09-25 10:25     ` Suzuki K Poulose
2018-09-17 10:41 ` [PATCH v5 18/18] kvm: arm64: Allow tuning the physical address size for VM Suzuki K Poulose
2018-09-17 14:20   ` Peter Maydell
2018-09-17 14:43     ` Suzuki K Poulose
2018-09-18  1:55   ` Peter Maydell [this message]
2018-09-18 15:16     ` Suzuki K Poulose
2018-09-18 15:36       ` Peter Maydell
2018-09-18 16:27         ` Suzuki K Poulose
2018-09-18 17:15           ` Peter Maydell
2018-09-19 10:03             ` Suzuki K Poulose
2018-09-25 10:00   ` Auger Eric
2018-09-25 10:24     ` Suzuki K Poulose
2018-09-17 10:41 ` [kvmtool PATCH v5 19/18] kvmtool: Allow backends to run checks on the KVM device fd Suzuki K Poulose
2018-09-17 10:41 ` [kvmtool PATCH v5 20/18] kvmtool: arm64: Add support for guest physical address size Suzuki K Poulose
2018-09-17 10:41 ` [kvmtool PATCH v5 21/18] kvmtool: arm64: Switch memory layout Suzuki K Poulose
2018-09-17 10:41 ` [kvmtool PATCH v5 22/18] kvmtool: arm: Add support for creating VM with PA size Suzuki K Poulose

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