From: Marc Zyngier <maz@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Fuad Tabba <tabba@google.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev
Subject: Re: [PATCH v4 0/4] KVM: arm64: Fix underallocation of storage for SVE state
Date: Fri, 05 Jul 2024 14:20:05 +0100 [thread overview]
Message-ID: <86a5iw3ri2.wl-maz@kernel.org> (raw)
In-Reply-To: <20240704-kvm-arm64-fix-pkvm-sve-vl-v4-0-b6898ab23dc4@kernel.org>
On Thu, 04 Jul 2024 18:28:15 +0100,
Mark Brown <broonie@kernel.org> wrote:
>
> As observed during review the pKVM support for saving host SVE state is
> broken if an asymmetric system has VLs larger than the maximum shared
> VL, fix this by discovering then using the maximum VL for allocations
> and using RDVL during the save/restore process.
I really don't see why we need such complexity here.
Fuad did post something[1] that did the trick with a far less invasive
change, and it really feels like we are putting the complexity at the
wrong place.
So what's wrong with that approach? I get that you want to shout about
secondary CPUs, but that's an orthogonal problem.
M.
[1] https://lore.kernel.org/r/20240606092623.2236172-1-tabba@google.com
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2024-07-05 13:20 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-04 17:28 [PATCH v4 0/4] KVM: arm64: Fix underallocation of storage for SVE state Mark Brown
2024-07-04 17:28 ` [PATCH v4 1/4] arm64/fpsimd: Introduce __bit_to_vl() helper Mark Brown
2024-07-04 17:28 ` [PATCH v4 2/4] arm64/fpsimd: Discover maximum vector length implemented by any CPU Mark Brown
2024-07-04 17:28 ` [PATCH v4 3/4] KVM: arm64: Fix FFR offset calculation for pKVM host state save and restore Mark Brown
2024-07-05 13:27 ` Marc Zyngier
2024-07-05 17:25 ` Mark Brown
2024-07-04 17:28 ` [PATCH v4 4/4] KVM: arm64: Avoid underallocating storage for host SVE state Mark Brown
2024-07-05 13:20 ` Marc Zyngier [this message]
2024-07-05 17:18 ` [PATCH v4 0/4] KVM: arm64: Fix underallocation of storage for " Mark Brown
2024-07-08 15:30 ` Dave Martin
2024-07-08 18:12 ` Mark Brown
2024-09-04 15:48 ` Mark Brown
2024-09-06 15:35 ` Fuad Tabba
2024-09-06 16:10 ` Mark Brown
2024-09-06 16:14 ` Fuad Tabba
2024-09-06 18:02 ` Mark Brown
2024-09-10 12:49 ` Fuad Tabba
2024-09-10 14:19 ` Mark Brown
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