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 18:15:04 +0100 [thread overview]
Message-ID: <CAFEAcA_tphfZ_BKfAYuefStTipta0notyAR=NCnWFJ6nRfERpg@mail.gmail.com> (raw)
In-Reply-To: <fec1a2e0-a45a-eb51-6ffe-2ac9b35acc45@arm.com>
On 18 September 2018 at 17:27, Suzuki K Poulose <Suzuki.Poulose@arm.com> wrote:
> ---
>
> "On arm64, the physical address size for a VM (IPA Size limit) is limited
> to 40bits by default. The limit can be configured if the host supports the
> extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use
> KVM_VM_TYPE_ARM_IPA_SIZE(IPA_Bits) to set the size in the machine type
> identifier, where IPA_Bits is the maximum width of any physical
> address used by the VM. The IPA_Bits is encoded in bits[7-0] of the
> machine type identifier.
>
> e.g, to configure a guest to use 48bit physical address size :
>
> vm_fd = ioctl(dev_fd, KVM_CREATE_VM, KVM_VM_TYPE_ARM_IPA_SIZE(48));
>
> The requested size (IPA_Bits) must be :
> 0 - Implies default 40bits (for backward compatibility)
>
> or
>
> N - Implies N bits, where N is a positive integer such that 32 <= N <=
> Host_IPA_Limit
>
> Host_IPA_Limit is the maximum possible value for IPA_Bits on the host and
> is dependent on the CPU capability and the kernel configuration. The limit
> can
> be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the KVM_CHECK_EXTENSION
> ioctl() at run-time.
>
> Please note that configuring the IPA size does not affect the capability
> exposed by the guest CPUs in ID_AA64MMFR0_EL1[PARange]. It only affects
> the guest to host physical address (stage2) translations setup by the host.
> "
Thanks, this is much clearer. The only bit I'm not sure about is that
last paragraph -- if I ask for a VM with a 48 bit address space why
don't we tell the guest that that's what it has ?
thanks
-- PMM
next prev parent reply other threads:[~2018-09-18 17:15 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
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 [this message]
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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