From: Marc Zyngier <maz@kernel.org>
To: Leonardo Bras <leo.bras@arm.com>
Cc: Oliver Upton <oupton@kernel.org>,
Fuad Tabba <fuad.tabba@linux.dev>,
Joey Gouly <joey.gouly@arm.com>,
Steffen Eiden <seiden@linux.ibm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Raghavendra Rao Ananta <rananta@google.com>,
Tian Zheng <zhengtian10@huawei.com>,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/5] KVM: arm64: Add KVM_PGTABLE_PROT_DIRTY
Date: Sun, 13 Sep 2026 10:09:25 +0100 [thread overview]
Message-ID: <86a4pl7c1m.wl-maz@kernel.org> (raw)
In-Reply-To: <20260901171558.2674031-3-leo.bras@arm.com>
On Tue, 01 Sep 2026 18:15:53 +0100,
Leonardo Bras <leo.bras@arm.com> wrote:
>
> Second step of changing the encoding for the Stage2 PTE descriptor,
> introduce the concept of dirty page, so we can have a writable but not
> dirty (WC) page, and a writable and dirty (WD) page.
Why should we care about *setting* the dirty bit in the PTE? Under
what circumstance do we want to establish a mapping as being dirty?
The whole point of DBM is to only set something dirty when it is
written to, and this patch breaks this invariant.
Maybe you have a good reason to do so, but that's not explained.
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-09-13 9:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 17:15 [RFC PATCH 0/5] KVM: arm64: New PTE dirty-page encoding, HAFDBS new usage Leonardo Bras
2026-09-01 17:15 ` [RFC PATCH 1/5] KVM: arm64: pgtables: Change write bit from S2AP_W to DBM Leonardo Bras
2026-09-13 9:00 ` Marc Zyngier
2026-09-01 17:15 ` [RFC PATCH 2/5] KVM: arm64: Add KVM_PGTABLE_PROT_DIRTY Leonardo Bras
2026-09-13 9:09 ` Marc Zyngier [this message]
2026-09-01 17:15 ` [RFC PATCH 3/5] KVM: arm64: Introduce a dedicated walker for stage2 write-protect Leonardo Bras
2026-09-01 17:15 ` [RFC PATCH 4/5] KVM: arm64: Add KVM_REQ_RELOAD_STAGE2 Leonardo Bras
2026-09-02 3:41 ` Tian Zheng
2026-09-02 10:53 ` Leonardo Bras
2026-09-01 17:15 ` [RFC PATCH 5/5] KVM: arm64: Enable HAFDBS for guests not on migration Leonardo Bras
2026-09-12 12:24 ` [RFC PATCH 0/5] KVM: arm64: New PTE dirty-page encoding, HAFDBS new usage Marc Zyngier
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