Re: [PATCH v2 4/7] entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM proper

From: Thomas Gleixner <tglx@linutronix.de>
To: Sean Christopherson <seanjc@google.com>,
	Marc Zyngier <maz@kernel.org>,
	Oliver Upton <oliver.upton@linux.dev>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Tianrui Zhao <zhaotianrui@loongson.cn>,
	Bibo Mao <maobibo@loongson.cn>,
	Huacai Chen <chenhuacai@kernel.org>,
	Anup Patel <anup@brainfault.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Uladzislau Rezki <urezki@gmail.com>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
	kvm@vger.kernel.org, loongarch@lists.linux.dev,
	kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
	linux-hyperv@vger.kernel.org, rcu@vger.kernel.org,
	Nuno Das Neves <nunodasneves@linux.microsoft.com>,
	Mukesh R <mrathor@linux.microsoft.com>
Subject: Re: [PATCH v2 4/7] entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM proper
Date: Tue, 02 Sep 2025 17:41:37 +0200	[thread overview]
Message-ID: <87wm6gzwsu.ffs@tglx> (raw)
In-Reply-To: <20250828000156.23389-5-seanjc@google.com>

On Wed, Aug 27 2025 at 17:01, Sean Christopherson wrote:
> Move KVM's morphing of pending signals into userspace exits into KVM
> proper, and drop the @vcpu param from xfer_to_guest_mode_handle_work().
> How KVM responds to -EINTR is a detail that really belongs in KVM itself,
> and invoking kvm_handle_signal_exit() from kernel code creates an inverted
> module dependency.  E.g. attempting to move kvm_handle_signal_exit() into
> kvm_main.c would generate an linker error when building kvm.ko as a module.
>
> Dropping KVM details will also converting the KVM "entry" code into a more
> generic virtualization framework so that it can be used when running as a
> Hyper-V root partition.
>
> Lastly, eliminating usage of "struct kvm_vcpu" outside of KVM is also nice
> to have for KVM x86 developers, as keeping the details of kvm_vcpu purely
> within KVM allows changing the layout of the structure without having to
> boot into a new kernel, e.g. allows rebuilding and reloading kvm.ko with a
> modified kvm_vcpu structure as part of debug/development.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

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