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

From: Marc Zyngier <maz@kernel.org>
To: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: kernel-team@android.com, kvm@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	George Cherian <gcherian@marvell.com>,
	"Zengtao \(B\)" <prime.zeng@hisilicon.com>,
	Andre Przywara <andre.przywara@arm.com>,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 00/17] KVM: arm64: Preliminary NV patches
Date: Tue, 07 Jul 2020 12:49:21 +0100	[thread overview]
Message-ID: <336e9d1e8d2566d131e4326d71ddd161@kernel.org> (raw)
In-Reply-To: <c5cd34b2-3360-e634-fe0f-9bbb91275235@arm.com>

On 2020-07-07 12:24, 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?

You need the slightly amended version (kvm-arm6/el2-obj-v4.1 from my 
tree).
Otherwise, just pick kvmarm/next, which has everything put together
in one scary lot.

Thanks,

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