From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 762B6C4167B for ; Tue, 27 Dec 2022 14:35:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References:Message-Id :MIME-Version:Subject:Date:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5hHbQQDWYEIb2ahRLBz8f5Cnf7fj1ztTm0krPNUrpiM=; b=reIXiBjM33ywit INWUJYNsGJxzopLlIvUzqrcmoNwrf4SpFF9GIE3a0tYjir5aTZyETATkFnydm+dBtRVc1gg56b8+j 5PplnCHSw7w4mQ2nFrBcuUMBbXno8t7ES5FApO4MLq2ZApqDF5wPemVZP6H9FWxF90OvcEoO1r/FG tWRjqesvdBEM1saMKhLeKQ5B/69LtEESn1GBplJl68aOzB6McWCf/zFQbsd//q1WqQeuEX1d7lSfa SqPblemrMGUb2+h7Ff/jU6CZEjZRHWZuyW2EBi534zZ8Iwp36Y0ZxyH3gYrdGYT6ac+460TRWYllV FOoBRO2c9VlUmDQ3R1jg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pAB22-00DhXq-RF; Tue, 27 Dec 2022 14:34:19 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pAB1v-00DhVl-Lj for linux-arm-kernel@lists.infradead.org; Tue, 27 Dec 2022 14:34:13 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8B0116115D; Tue, 27 Dec 2022 14:34:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F315DC43396; Tue, 27 Dec 2022 14:34:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672151650; bh=sG9v2Kt6FCDopacILFBaWr43bInSjVesEWi3vJNnqW4=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ql5BiyIX48YzftPSFqt6JMm9s+SE9cyeMtoJj8ABqFWIT8glzycmauwdBDpRoucfq KLOJfrpdIUVeOll/uL4x5gTwlJICF24BIrrum5cthr9kgujRusajhsklEIolz9YnGA 5F4t/Y0VT7fglOvQir3yoBesSKjvvToPHEFtzMHTZjMThuMKYgxAbYp2/MOKU1Dciu HIqEsW/k29bMwK+rU+l6UIcny0IYHacEct+Z1vKUhLKuJ/2fQzjpoDkS+CPj7OcnvD v1eYQAb+aGKQXKvo9AvsfzLhF5f00aM8tznKN3yeKYh3MDN6GnRge4uvxmgUT1FI/Z 36pN7qx1cugOQ== From: Mark Brown Date: Tue, 27 Dec 2022 14:33:38 +0000 Subject: [PATCH 1/3] KVM: arm64: Document check for TIF_FOREIGN_FPSTATE MIME-Version: 1.0 Message-Id: <20221214-kvm-arm64-sme-context-switch-v1-1-383b4699de06@kernel.org> References: <20221214-kvm-arm64-sme-context-switch-v1-0-383b4699de06@kernel.org> In-Reply-To: <20221214-kvm-arm64-sme-context-switch-v1-0-383b4699de06@kernel.org> To: Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Catalin Marinas , Will Deacon Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, Mark Brown X-Mailer: b4 0.12-dev-7ab1d X-Developer-Signature: v=1; a=openpgp-sha256; l=1080; i=broonie@kernel.org; h=from:subject:message-id; bh=sG9v2Kt6FCDopacILFBaWr43bInSjVesEWi3vJNnqW4=; b=owGbwMvMwMWocq27KDak/QLjabUkhuTVTFG+b5jjFj36tUB09rTe2eG1H++/KroWfVNXqvipTb7X 9NqLnYzGLAyMXAyyYoosa59lrEoPl9g6/9H8VzCDWJlApjBwcQrARDz2s/+VOKDNxvzHOOqFfkx46o TlTC+27urdcoK3Ol3qoF1hgzvjc9Od9lYTLFf6hLBOlw3anVx14eK6v5EFM1zmNonwm/BX+P28OXFz 0PEZfXJWm0u/6ts+kpNdaS+Rt9eC8XBIjPJvkZBDbXa5rBvjijJFCqW3POy5WzZ7anCtYv16gbK3D4 23L7aX7AmfIPb42lbhbS42CxuFt2QWS7o++HNyszLP5LgGJz3ZbzZJRsskJvqeiJ/At0rT2OjmvdRs zwv5Hoc8K/l0c1b21rjczS7QO7ns1LLunvVGTafOdSRysMUo2RW6slXHdX8SvDn9rmZ4hjVH4T8lmd Lcv7/09BecWLm/wMjmxKwY1ZZaAA== X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221227_063411_836717_6B03BB82 X-CRM114-Status: GOOD ( 12.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org In kvm_arch_vcpu_load_fp() we unconditionally set the current FP state to FP_STATE_HOST_OWNED, this will be overridden to FP_STATE_NONE if TIF_FOREIGN_FPSTATE is set but the check is deferred until kvm_arch_vcpu_ctxflush_fp() where we are no longer preemptable. Add a comment to this effect to help avoid people being concerned about the lack of a check and discover where the check is done. Signed-off-by: Mark Brown --- arch/arm64/kvm/fpsimd.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 02dd7e9ebd39..6c1cb945c777 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -81,6 +81,11 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) fpsimd_kvm_prepare(); + /* + * We will check TIF_FOREIGN_FPSTATE just before entering the + * guest in kvm_arch_vcpu_ctxflush_fp() and override this to + * FP_STATE_FREE if the flag set. + */ vcpu->arch.fp_state = FP_STATE_HOST_OWNED; vcpu_clear_flag(vcpu, HOST_SVE_ENABLED); -- 2.30.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel