From: Catalin Marinas <catalin.marinas@arm.com>
To: Shradha Gupta <shradhagupta@linux.microsoft.com>
Cc: Will Deacon <will@kernel.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
Long Li <longli@microsoft.com>,
linux-arm-kernel@lists.infradead.org,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <maz@kernel.org>,
Michael Kelley <mikelley@microsoft.com>,
Shradha Gupta <shradhagupta@microsoft.com>
Subject: Re: [RFC PATCH 0/2] arm64/hyperv: Enable kexec reboot support
Date: Fri, 21 Aug 2026 11:14:49 +0100 [thread overview]
Message-ID: <aoglGZD7ntLJkmcO@arm.com> (raw)
In-Reply-To: <20260814093133.3191250-1-shradhagupta@linux.microsoft.com>
On Fri, Aug 14, 2026 at 02:31:28AM -0700, Shradha Gupta wrote:
> Kexec reboot consistently fails on ARM64 Hyper-V guests (Azure VMs).
> During the kexec shutdown path, VMBus channels are never cleaned up,
> so in the fresh kexec kernel startup hv_acpi_init() blocks because
> the hypervisor still holds the old kernel's VMBus session open.
>
> This is because ARM64 lacks the VMBus teardown that x86 performs during
> kexec via hv_machine_shutdown(). On x86, machine_ops.shutdown is
> overridden to send CHANNELMSG_UNLOAD and disable SynIC before CPUs
> go offline. ARM64 has no equivalent mechanism.
I'm really not keen on such hook, a bare pointer you set elsewhere. Not
sure it was discussed before but can you not use the syscore_shutdown()
mechanism? This hook got added in 2023, so the 2022 discussion you
referenced precedes it.
--
Catalin
prev parent reply other threads:[~2026-08-21 10:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-14 9:31 [RFC PATCH 0/2] arm64/hyperv: Enable kexec reboot support Shradha Gupta
2026-08-14 9:31 ` [RFC PATCH 1/2] arm64: Add pre-shutdown hook to machine_shutdown() Shradha Gupta
2026-08-14 9:32 ` [RFC PATCH 2/2] arm64/hyperv: Add kexec handler using machine_shutdown hook Shradha Gupta
2026-08-21 9:17 ` [RFC PATCH 0/2] arm64/hyperv: Enable kexec reboot support Shradha Gupta
2026-08-21 10:14 ` Catalin Marinas [this message]
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