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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606567625; bh=lnhjrd1BY+4XT/salWuXAQXDGdluOebgvvtHAouCinc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fINe9zgg4BEo7DfBbGMcvdXT8bPDtBIBZgP6f6gxVZpUYSoriqEFshlbY+fjTA0A6 QsBCMpyTQAtpWVlYOyszH/w67Itf4NHxOXc9OoMTYyOJLehFCg7qOxqG98YkGtV5uy NgE5A5J2H092MPpM2lp/0URKigLApTzWr8KgVVZc= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1kizd1-00EHHF-S1; Sat, 28 Nov 2020 12:47:04 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Subject: [PATCH 1/2] arm64: Make the Meltdown mitigation state available Date: Sat, 28 Nov 2020 12:46:58 +0000 Message-Id: <20201128124659.669578-2-maz@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201128124659.669578-1-maz@kernel.org> References: <20201128124659.669578-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, will@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201128_074708_737798_08453365 X-CRM114-Status: GOOD ( 15.52 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: James Morse , kernel-team@android.com, Will Deacon , Julien Thierry , Suzuki K Poulose Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Our Meltdown mitigation state isn't exposed outside of cpufeature.c, contrary to the rest of the Spectre mitigation state. As we are going to use it in KVM, expose a arm64_get_meltdown_state() helper which returns the same possible values as arm64_get_spectre_v?_state(). Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/spectre.h | 2 ++ arch/arm64/kernel/cpufeature.c | 20 +++++++++++++++++--- 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/spectre.h b/arch/arm64/include/asm/spectre.h index fcdfbce302bd..52e788981f4a 100644 --- a/arch/arm64/include/asm/spectre.h +++ b/arch/arm64/include/asm/spectre.h @@ -29,4 +29,6 @@ bool has_spectre_v4(const struct arm64_cpu_capabilities *cap, int scope); void spectre_v4_enable_mitigation(const struct arm64_cpu_capabilities *__unused); void spectre_v4_enable_task_mitigation(struct task_struct *tsk); +enum mitigation_state arm64_get_meltdown_state(void); + #endif /* __ASM_SPECTRE_H */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 6f36c4f62f69..280b10762f6b 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -2846,14 +2846,28 @@ static int __init enable_mrs_emulation(void) core_initcall(enable_mrs_emulation); +enum mitigation_state arm64_get_meltdown_state(void) +{ + if (__meltdown_safe) + return SPECTRE_UNAFFECTED; + + if (arm64_kernel_unmapped_at_el0()) + return SPECTRE_MITIGATED; + + return SPECTRE_VULNERABLE; +} + ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf) { - if (__meltdown_safe) + switch (arm64_get_meltdown_state()) { + case SPECTRE_UNAFFECTED: return sprintf(buf, "Not affected\n"); - if (arm64_kernel_unmapped_at_el0()) + case SPECTRE_MITIGATED: return sprintf(buf, "Mitigation: PTI\n"); - return sprintf(buf, "Vulnerable\n"); + default: + return sprintf(buf, "Vulnerable\n"); + } }