From: Oliver Upton <oupton@kernel.org>
To: Marc Zyngier <maz@kernel.org>, Fuad Tabba <fuad.tabba@linux.dev>
Cc: Oliver Upton <oupton@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Steffen Eiden <seiden@linux.ibm.com>,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, tabba@google.com
Subject: Re: [PATCH 0/2] KVM: arm64: Fix host-directed debug for non-protected pKVM guests
Date: Fri, 31 Jul 2026 11:51:45 -0700 [thread overview]
Message-ID: <178552142330.30097.7850333849629828287.b4-ty@kernel.org> (raw)
In-Reply-To: <20260726143643.303456-1-fuad.tabba@linux.dev>
On Sun, 26 Jul 2026 15:36:41 +0100, Fuad Tabba wrote:
> Under pKVM, host-directed hardware debug of a non-protected guest
> (KVM_GUESTDBG_USE_HW) and userspace single-step never fire.
>
> When the host owns the debug registers, the world switch loads
> MDSCR_EL1 from external_mdscr_el1, where the host's MDE/KDE/SS bits
> live. flush_debug_state() copies the guest's debug_owner and the
> owner-selected debug register state to the hyp vCPU, but not
> external_mdscr_el1, so the field reaches hardware as zero and the debug
> exceptions stay disabled. Patch 1 propagates it.
>
> [...]
Applied to next, thanks!
[1/2] KVM: arm64: Flush external_mdscr_el1 to the pKVM hyp vCPU
https://git.kernel.org/kvmarm/kvmarm/c/119a9a23fbae
[2/2] KVM: arm64: selftests: Add a userspace watchpoint test
https://git.kernel.org/kvmarm/kvmarm/c/3be99f8751c9
--
Best,
Oliver
prev parent reply other threads:[~2026-07-31 18:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-26 14:36 Fuad Tabba
2026-07-26 14:36 ` [PATCH 1/2] KVM: arm64: Flush external_mdscr_el1 to the pKVM hyp vCPU Fuad Tabba
2026-07-26 14:36 ` [PATCH 2/2] KVM: arm64: selftests: Add a userspace watchpoint test Fuad Tabba
2026-07-31 18:51 ` Oliver Upton [this message]
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