From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 423971DFF1; Mon, 20 Nov 2023 13:10:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cgurBvk+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16470C433CC; Mon, 20 Nov 2023 13:10:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700485858; bh=5DBiFNgj+CREZmY9jeeRQhQKYcgewSdvLDerRT8EBow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cgurBvk+NHNAqalG1NLzymPZ3yNuahqZ8KWV/fKJ1CQfeQ4LEynSrTE0dsjRy8Hqw DyfJB9P7VNkX2kf3KpiBpQnEe0jhQRjgjdSBhGqexZXiUCTT1ndyxhGTXQ97LmZFNh USvoSR7v2OqzIZPsQgD2DbtK7Jo30HmZQZEOymDk/3Ws09fnP3174i30lhI3c2GP4x n2P9lUZLuTs3N7lFoUB49aKl4BswKi63WqSvX0JN00lEPI6an4mnnHZ6kKQIZGSp0q jt6BwuNeQWIsHD0nWAOC1EjFu+x63srsdf/PaqomnsbaoW+yJKV4OvgNZUGYzN1I5N aHPy2he7kaTJw== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1r543E-00EjnU-97; Mon, 20 Nov 2023 13:10:56 +0000 From: Marc Zyngier To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Alexandru Elisei , Andre Przywara , Chase Conklin , Christoffer Dall , Ganapatrao Kulkarni , Darren Hart , Jintack Lim , Russell King , Miguel Luis , James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu Subject: [PATCH v11 28/43] KVM: arm64: nv: Publish emulated timer interrupt state in the in-memory state Date: Mon, 20 Nov 2023 13:10:12 +0000 Message-Id: <20231120131027.854038-29-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231120131027.854038-1-maz@kernel.org> References: <20231120131027.854038-1-maz@kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, alexandru.elisei@arm.com, andre.przywara@arm.com, chase.conklin@arm.com, christoffer.dall@arm.com, gankulkarni@os.amperecomputing.com, darren@os.amperecomputing.com, jintack@cs.columbia.edu, rmk+kernel@armlinux.org.uk, miguel.luis@oracle.com, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false With FEAT_NV2, the EL0 timer state is entirely stored in memory, meaning that the hypervisor can only provide a very poor emulation. The only thing we can really do is to publish the interrupt state in the guest view of CNT{P,V}_CTL_EL0, and defer everything else to the next exit. Only FEAT_ECV will allow us to fix it, at the cost of extra trapping. Suggested-by: Chase Conklin Suggested-by: Ganapatrao Kulkarni Signed-off-by: Marc Zyngier --- arch/arm64/kvm/arch_timer.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c index e3f6feef2c83..dba92bbe4617 100644 --- a/arch/arm64/kvm/arch_timer.c +++ b/arch/arm64/kvm/arch_timer.c @@ -447,6 +447,25 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, { int ret; + /* + * Paper over NV2 brokenness by publishing the interrupt status + * bit. This still results in a poor quality of emulation (guest + * writes will have no effect until the next exit). + * + * But hey, it's fast, right? + */ + if (is_hyp_ctxt(vcpu) && + (timer_ctx == vcpu_vtimer(vcpu) || timer_ctx == vcpu_ptimer(vcpu))) { + u32 ctl = timer_get_ctl(timer_ctx); + + if (new_level) + ctl |= ARCH_TIMER_CTRL_IT_STAT; + else + ctl &= ~ARCH_TIMER_CTRL_IT_STAT; + + timer_set_ctl(timer_ctx, ctl); + } + timer_ctx->irq.level = new_level; trace_kvm_timer_update_irq(vcpu->vcpu_id, timer_irq(timer_ctx), timer_ctx->irq.level); -- 2.39.2