Re: [PATCH v3 00/17] KVM: arm64: Preliminary NV patches

From: Alexandru Elisei <alexandru.elisei@arm.com>
To: Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: kernel-team@android.com, Andre Przywara <andre.przywara@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	George Cherian <gcherian@marvell.com>,
	"Zengtao (B)" <prime.zeng@hisilicon.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH v3 00/17] KVM: arm64: Preliminary NV patches
Date: Tue, 7 Jul 2020 12:48:01 +0100	[thread overview]
Message-ID: <45c17750-1cc2-9a44-9b71-55481870f522@arm.com> (raw)
In-Reply-To: <c5cd34b2-3360-e634-fe0f-9bbb91275235@arm.com>

Hi,

On 7/7/20 12:24 PM, Alexandru Elisei wrote:
> Hi,
>
> On 7/6/20 1:54 PM, Marc Zyngier wrote:
>> Hi all,
>>
>> In order not to repeat the 90+ patch series that resulted in a
>> deafening silence last time, I've extracted a smaller set of patches
>> that form the required dependencies that allow the rest of the 65 NV
>> patches to be added on top. Yes, it is that bad.
>>
>> The one real feature here is support for the ARMv8.4-TTL extension at
>> Stage-2 only. The reason to support it is that it helps the hypervisor
>> a lot when it comes to finding out how much to invalidate. It is thus
>> always "supported" with NV.
>>
>> The rest doesn't contain any functionality change. Most of it reworks
>> existing data structures and adds new accessors for the things that
>> get moved around. The reason for this is that:
>>
>> - With NV, we end-up with multiple Stage-2 MMU contexts per VM instead
>>   of a single one. This requires we divorce struct kvm from the S2 MMU
>>   configuration. Of course, we stick with a single MMU context for now.
>>
>> - With ARMv8.4-NV, a number of system register accesses are turned
>>   into memory accesses into the so-called VNCR page. It is thus
>>   convenient to make this VNCR page part of the vcpu context and avoid
>>   copying data back and forth. For this to work, we need to make sure
>>   that all the VNCR-aware sysregs are moved into our per-vcpu sys_regs
>>   array instead of leaving in other data structures (the timers, for
>>   example). The VNCR page itself isn't introduced with these patches.
>>
>> - As some of these data structures change, we need a way to isolate
>>   the userspace ABI from such change.
>>
>> There is also a number of cleanups that were in the full fat series
>> that I decided to move early to get them out of the way.
>>
>> The whole this is a bit of a mix of vaguely unrelated "stuff", but it
>> all comes together if you look at the final series. This applies on
>> top of David Brazdil's series splitting the VHE and nVHE objects.
>>
>> I plan on taking this early into v5.9, and I really mean it this time!
>>
>> Catalin: How do you want to proceed for patches 2, 3, and 4? I could
>> make a stable branch that gets you pull into the arm64 tree, or the
>> other way around. Just let me know.
>>
>> Thanks,
>>
>> 	M.
>>
>> * From v2:
>>   - Rebased on top of David's el2-obj series
> I tried to apply the patches on top of v5.8-rc1, but I get a conflict on the very
> first patch. I guess it's because I don't have the el2-obj series. Is that v4 of
> "Split off nVHE hyp code" patches from David Brazil?

Nevermind, figured it out and used your kvm-arm64/el2-obj-4.1 branch as a base.

Thanks,
Alex