From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794064608; b=ZkGFTnMzEznuIGL2vr8b4xh8yEIjvYkTEpPHj/wuNT3SAy9i79+OI37Y8OV8RN7K6/ZJ 1sPtTzRU/8oa5a54FMznwfsCRKXneGohOb8XmTAy+nROay53eazWLaA+msUFw2P9uA1qD 0qiCbid096I3BR/T/OpVDlKe+EwMuKb459E3qbWL8hhHlK5OFIoUK7agitAH6G7GippmM cRPnsEuAlboVB9mpbQzyVpKYZhQ62p5R8VRUCN/ZQGD8IU1ctT/2cTtGH+hkRe1rmeH9r zfOTTVqDRshzKz1lLpzfNKL9KmyjgwUd6DKG0tyuju0FRTB4OxtDO1oUqTbVbL5lmtA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794064608; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=Cp428scmMcMNcwyR4rWToLPyzEMoGHoZDoTRMd/JM9Q=; b=vPQKvPbLo1tUHfi21x8+ZpYcDkF4cRFDTzaY9+g/001OznBPbnQMqoBBL3ttd2y81dEw aeLq3QyQnUXDg1afnKIfEZUwbx0BtkxeV6ALRUk7e/QM57oG9D/l5TFTNFU6cCLhCCqcc 0dEPvo6ZaN4r2oQgdy6CD6hndDA0dQgg8yHigm47wOjWbrI3Vc/oNRGVX9UdLGG0Pz0vc fLOVg32kTQjIJXCl5rC7t5hEj8bF/wp1rgwc0KpA18iQfrHRQ/j6S2oLmJRjEftDOLgdr T5ORvYlXa6vXP3hL5sUBG+UlQBslAnaKF4YlYmsvacFj3fqCAVSR3YclpCG6ocJZW3Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=OnrAu4qh; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C40E606E8FE; Sat, 7 Nov 2026 15:16:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=OnrAu4qh Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DE141F008A2; Sat, 7 Nov 2026 15:16:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794064607; bh=Cp428scmMcMNcwyR4rWToLPyzEMoGHoZDoTRMd/JM9Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OnrAu4qhwGlM0R6Ia2jBgbrpT8EfRq30fA+HK+LkaIFdbWCXlWo/InR+15gAxOh44 ZvOcgWZEI1Av7zw8sCfYoEQp6gf+mvv8XoJ99r5p7KSPPexWsnDE+fI+jcNjqRtHlG WIy2Ae1QWOKOxq6NCtaZcpvIvZe+b1XX/p792Nro= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vincent Donnefort , Fuad Tabba , Marc Zyngier , Sasha Levin Subject: [PATCH 7.3 0619/1257] KVM: arm64: Prevent 64-bit overflow when computing hyp clock rate Date: Sat, 7 Nov 2026 08:48:35 -0500 Message-ID: <20261107134956.396209498@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134939.434104957@linuxfoundation.org> References: <20261107134939.434104957@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vincent Donnefort [ Upstream commit 6164ce3491bcc3a27a2e2e9260a286eb2df2301e ] The hypervisor clock rate is delta_cycles * NSEC_PER_SEC / delta_boot. It is computed whenever a deviation occurs. If the delta between two rate updates is big enough, delta_cycles * NSEC_PER_SEC will overflow. Prevent overflow with mul_u64_u64_div_u64(). And as a bonus, simplify the clock estimation with mul_u64_u32_shr(). Fixes: b22888917fa4 ("KVM: arm64: Sync boot clock with the nVHE/pKVM hyp") Cc: stable@vger.kernel.org Signed-off-by: Vincent Donnefort Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Link: https://patch.msgid.link/20261008104212.3134550-2-vdonnefort@google.com Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin --- arch/arm64/kvm/hyp_trace.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c index 9644c424819b7..c60d7dfbf5e26 100644 --- a/arch/arm64/kvm/hyp_trace.c +++ b/arch/arm64/kvm/hyp_trace.c @@ -59,14 +59,8 @@ static void __hyp_clock_work(struct work_struct *work) if (hyp_clock->mult) { u64 err, cur = delta_cycles; - if (WARN_ON_ONCE(cur >= hyp_clock->cyc_overflow64)) { - __uint128_t tmp = (__uint128_t)cur * hyp_clock->mult; - - cur = tmp >> hyp_clock->shift; - } else { - cur *= hyp_clock->mult; - cur >>= hyp_clock->shift; - } + WARN_ON_ONCE(cur >= hyp_clock->cyc_overflow64); + cur = mul_u64_u32_shr(cur, hyp_clock->mult, hyp_clock->shift); cur += hyp_clock->boot; err = abs_diff(cur, boot); @@ -84,7 +78,7 @@ static void __hyp_clock_work(struct work_struct *work) err / NSEC_PER_USEC); } - rate = div64_u64(delta_cycles * NSEC_PER_SEC, delta_boot); + rate = mul_u64_u64_div_u64(delta_cycles, NSEC_PER_SEC, delta_boot); clocks_calc_mult_shift(&hyp_clock->mult, &hyp_clock->shift, rate, NSEC_PER_SEC, CLOCK_MAX_CONVERSION_S); -- 2.53.0