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From: Marc Zyngier <maz@kernel.org>
To: James Morse <james.morse@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	kvm@vger.kernel.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
	Jintack Lim <jintack@cs.columbia.edu>,
	Andre Przywara <andre.przywara@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	kvmarm@lists.cs.columbia.edu, Will Deacon <will@kernel.org>,
	George Cherian <gcherian@marvell.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	"Zengtao \(B\)" <prime.zeng@hisilicon.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 20/26] KVM: arm64: Move ELR_EL1 to the system register array
Date: Wed, 27 May 2020 11:36:39 +0100	[thread overview]
Message-ID: <d7cb5dc4656cab36db79b0eaf3737221@kernel.org> (raw)
In-Reply-To: <b6a08ca6-1682-4fa6-e8f4-bb4adba5d19a@arm.com>

On 2020-05-26 17:29, James Morse wrote:
> Hi Marc,
> 
> On 22/04/2020 13:00, Marc Zyngier wrote:
>> As ELR-EL1 is a VNCR-capable register with ARMv8.4-NV, let's move it 
>> to
>> the sys_regs array and repaint the accessors. While we're at it, let's
>> kill the now useless accessors used only on the fault injection path.
> 
> Reviewed-by: James Morse <james.morse@arm.com>
> 
> 
> A curiosity:
> 
>> diff --git a/arch/arm64/include/asm/kvm_host.h 
>> b/arch/arm64/include/asm/kvm_host.h
>> index 95977b80265ce..46949fce3e813 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -184,6 +184,8 @@ enum vcpu_sysreg {
> 
> Comment above the enum has some claims about the order, but its
> already out of order with
> __vcpu_read_sys_reg_from_cpu()... (PAR_EL1 being the culprit)

This comment dates back from the original assembly implementation,
where I was paranoid about accessing the sys_regs array in strict
order to maximize the chances of the prefetcher doing the right thing.

As always with premature optimization, it was worthless, and moving
things to C forced us to do things differently anyway (not to mention
VHE...).

I'll delete the comment in a separate patch.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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  reply	other threads:[~2020-05-27 10:36 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-22 12:00 [PATCH 00/26] KVM: arm64: Preliminary NV patches Marc Zyngier
2020-04-22 12:00 ` [PATCH 01/26] KVM: arm64: Check advertised Stage-2 page size capability Marc Zyngier
2020-04-22 13:40   ` Suzuki K Poulose
2020-04-22 14:07     ` Marc Zyngier
2020-04-22 14:14       ` Suzuki K Poulose
2020-05-07 11:42   ` Alexandru Elisei
2020-04-22 12:00 ` [PATCH 02/26] KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h Marc Zyngier
2020-04-22 13:51   ` Suzuki K Poulose
2020-04-22 13:59     ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 03/26] KVM: arm64: Factor out stage 2 page table data from struct kvm Marc Zyngier
2020-05-05 15:26   ` Andrew Scull
2020-05-05 16:32     ` Marc Zyngier
2020-05-05 17:23       ` Andrew Scull
2020-05-05 18:10         ` Marc Zyngier
2020-05-05 16:03   ` James Morse
2020-05-05 17:59     ` Marc Zyngier
2020-05-06  9:30       ` Marc Zyngier
2020-05-11 16:38   ` Alexandru Elisei
2020-05-12 11:17     ` James Morse
2020-05-12 15:47       ` Alexandru Elisei
2020-05-12 16:13         ` James Morse
2020-05-12 16:53       ` Alexandru Elisei
2020-05-27  8:41         ` Marc Zyngier
2020-05-27  8:45           ` Alexandru Elisei
2020-04-22 12:00 ` [PATCH 04/26] arm64: Detect the ARMv8.4 TTL feature Marc Zyngier
2020-04-27 15:55   ` Suzuki K Poulose
2020-04-22 12:00 ` [PATCH 05/26] arm64: Document SW reserved PTE/PMD bits in Stage-2 descriptors Marc Zyngier
2020-05-05 15:59   ` Andrew Scull
2020-05-06  9:39     ` Marc Zyngier
2020-05-06 10:11       ` Andrew Scull
2020-04-22 12:00 ` [PATCH 06/26] arm64: Add level-hinted TLB invalidation helper Marc Zyngier
2020-05-05 17:16   ` Andrew Scull
2020-05-06  8:05     ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 07/26] KVM: arm64: Add a level hint to __kvm_tlb_flush_vmid_ipa Marc Zyngier
2020-05-07 15:08   ` Andrew Scull
2020-05-07 15:13     ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 08/26] KVM: arm64: Use TTL hint in when invalidating stage-2 translations Marc Zyngier
2020-05-07 15:13   ` Andrew Scull
2020-05-12 12:04     ` James Morse
2020-05-13  9:06       ` Andrew Scull
2020-05-27  8:59         ` Marc Zyngier
2020-05-12 17:26   ` James Morse
2020-04-22 12:00 ` [PATCH 09/26] KVM: arm64: vgic-v3: Take cpu_if pointer directly instead of vcpu Marc Zyngier
2020-05-07 16:26   ` James Morse
2020-05-08 12:20     ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 10/26] KVM: arm64: Refactor vcpu_{read,write}_sys_reg Marc Zyngier
2020-05-26 16:28   ` James Morse
2020-05-27 10:04     ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 11/26] KVM: arm64: Add missing reset handlers for PMU emulation Marc Zyngier
2020-05-26 16:29   ` James Morse
2020-04-22 12:00 ` [PATCH 12/26] KVM: arm64: Move sysreg reset check to boot time Marc Zyngier
2020-04-22 12:00 ` [PATCH 13/26] KVM: arm64: Introduce accessor for ctxt->sys_reg Marc Zyngier
2020-04-22 12:00 ` [PATCH 14/26] KVM: arm64: hyp: Use ctxt_sys_reg/__vcpu_sys_reg instead of raw sys_regs access Marc Zyngier
2020-04-22 12:00 ` [PATCH 15/26] KVM: arm64: sve: Use __vcpu_sys_reg() " Marc Zyngier
2020-04-22 12:00 ` [PATCH 16/26] KVM: arm64: pauth: Use ctxt_sys_reg() " Marc Zyngier
2020-04-22 12:00 ` [PATCH 17/26] KVM: arm64: debug: " Marc Zyngier
2020-04-22 12:00 ` [PATCH 18/26] KVM: arm64: Don't use empty structures as CPU reset state Marc Zyngier
2020-04-24  4:07   ` Zenghui Yu
2020-04-24  7:45     ` Marc Zyngier
2020-04-28  1:34       ` Zengtao (B)
2020-04-22 12:00 ` [PATCH 19/26] KVM: arm64: Make struct kvm_regs userspace-only Marc Zyngier
2020-05-26 16:29   ` James Morse
2020-05-27 10:22     ` Marc Zyngier
2020-04-22 12:00 ` [PATCH 20/26] KVM: arm64: Move ELR_EL1 to the system register array Marc Zyngier
2020-05-26 16:29   ` James Morse
2020-05-27 10:36     ` Marc Zyngier [this message]
2020-04-22 12:00 ` [PATCH 21/26] KVM: arm64: Move SP_EL1 " Marc Zyngier
2020-05-26 16:29   ` James Morse
2020-04-22 12:00 ` [PATCH 22/26] KVM: arm64: Disintegrate SPSR array Marc Zyngier
2020-05-26 16:30   ` James Morse
2020-04-22 12:00 ` [PATCH 23/26] KVM: arm64: Move SPSR_EL1 to the system register array Marc Zyngier
2020-05-26 16:30   ` James Morse
2020-04-22 12:00 ` [PATCH 24/26] KVM: arm64: timers: Rename kvm_timer_sync_hwstate to kvm_timer_sync_user Marc Zyngier
2020-04-22 12:00 ` [PATCH 25/26] KVM: arm64: timers: Move timer registers to the sys_regs file Marc Zyngier
2020-04-22 12:00 ` [PATCH 26/26] KVM: arm64: Parametrize exception entry with a target EL Marc Zyngier
2020-05-19 10:44   ` Mark Rutland
2020-05-27  9:34     ` Marc Zyngier
2020-05-27 14:41       ` Mark Rutland

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