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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5737CC43334 for ; Mon, 11 Jul 2022 23:25:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231562AbiGKXZG (ORCPT ); Mon, 11 Jul 2022 19:25:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230105AbiGKXZD (ORCPT ); Mon, 11 Jul 2022 19:25:03 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BF947B34E; Mon, 11 Jul 2022 16:25:02 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id AB7ABB81628; Mon, 11 Jul 2022 23:25:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCF81C341C8; Mon, 11 Jul 2022 23:24:58 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="CttgkQrL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1657581898; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=s3ZWXFpSLw1Egru9zwBfQoIZtWCngWwCiA7KZG1VwQ0=; b=CttgkQrLrSDSjhJmz8NDXtiAxccC4t7n/WfbBVSBI2XIWHOLa//9hItdww4pzUvxGfTyEU qCyTWcp7lRrraQv30LtjMc6WRyx6PIseNn11DlDJ4xr/HasAN5d2XYnYskDkZhxjammEUi roKECX+DbC0UQckAFqWkk/yENNqiwa8= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 03227f56 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Mon, 11 Jul 2022 23:24:57 +0000 (UTC) From: "Jason A. Donenfeld" To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au, sachinp@linux.ibm.com, linux-kernel@vger.kernel.org Cc: "Jason A. Donenfeld" , stable@vger.kernel.org Subject: [PATCH v5 2/2] powerpc/kvm: don't crash on missing rng, and use darn Date: Tue, 12 Jul 2022 01:24:48 +0200 Message-Id: <20220711232448.136765-3-Jason@zx2c4.com> In-Reply-To: <20220711232448.136765-1-Jason@zx2c4.com> References: <20220711232448.136765-1-Jason@zx2c4.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On POWER8 systems that don't have ibm,power-rng available, a guest that ignores the KVM_CAP_PPC_HWRNG flag and calls H_RANDOM anyway will dereference a NULL pointer. And on machines with darn instead of ibm,power-rng, H_RANDOM won't work at all. This patch kills two birds with one stone, by routing H_RANDOM calls to ppc_md.get_random_seed, and doing the real mode check inside of it. Cc: stable@vger.kernel.org # v4.1+ Cc: Michael Ellerman Tested-by: Sachin Sant Fixes: e928e9cb3601 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.") Signed-off-by: Jason A. Donenfeld --- arch/powerpc/include/asm/archrandom.h | 5 ---- arch/powerpc/kvm/book3s_hv_builtin.c | 7 +++--- arch/powerpc/platforms/powernv/rng.c | 34 +++++++-------------------- 3 files changed, 12 insertions(+), 34 deletions(-) diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h index 11d4815841ab..3af27bb84a3d 100644 --- a/arch/powerpc/include/asm/archrandom.h +++ b/arch/powerpc/include/asm/archrandom.h @@ -38,12 +38,7 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v) #endif /* CONFIG_ARCH_RANDOM */ #ifdef CONFIG_PPC_POWERNV -int pnv_hwrng_present(void); int pnv_get_random_long(unsigned long *v); -int pnv_get_random_real_mode(unsigned long *v); -#else -static inline int pnv_hwrng_present(void) { return 0; } -static inline int pnv_get_random_real_mode(unsigned long *v) { return 0; } #endif #endif /* _ASM_POWERPC_ARCHRANDOM_H */ diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c index 799d40c2ab4f..3abaef5f9ac2 100644 --- a/arch/powerpc/kvm/book3s_hv_builtin.c +++ b/arch/powerpc/kvm/book3s_hv_builtin.c @@ -19,7 +19,7 @@ #include #include #include -#include +#include #include #include #include @@ -176,13 +176,14 @@ EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode); int kvmppc_hwrng_present(void) { - return pnv_hwrng_present(); + return ppc_md.get_random_seed != NULL; } EXPORT_SYMBOL_GPL(kvmppc_hwrng_present); long kvmppc_rm_h_random(struct kvm_vcpu *vcpu) { - if (pnv_get_random_real_mode(&vcpu->arch.regs.gpr[4])) + if (ppc_md.get_random_seed && + ppc_md.get_random_seed(&vcpu->arch.regs.gpr[4])) return H_SUCCESS; return H_HARDWARE; diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c index b5cd82eab9b3..196aa70fe043 100644 --- a/arch/powerpc/platforms/powernv/rng.c +++ b/arch/powerpc/platforms/powernv/rng.c @@ -29,15 +29,6 @@ struct pnv_rng { static DEFINE_PER_CPU(struct pnv_rng *, pnv_rng); -int pnv_hwrng_present(void) -{ - struct pnv_rng *rng; - - rng = get_cpu_var(pnv_rng); - put_cpu_var(rng); - return rng != NULL; -} - static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val) { unsigned long parity; @@ -58,17 +49,6 @@ static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val) return val; } -int pnv_get_random_real_mode(unsigned long *v) -{ - struct pnv_rng *rng; - - rng = raw_cpu_read(pnv_rng); - - *v = rng_whiten(rng, __raw_rm_readq(rng->regs_real)); - - return 1; -} - static int pnv_get_random_darn(unsigned long *v) { unsigned long val; @@ -105,12 +85,14 @@ int pnv_get_random_long(unsigned long *v) { struct pnv_rng *rng; - rng = get_cpu_var(pnv_rng); - - *v = rng_whiten(rng, in_be64(rng->regs)); - - put_cpu_var(rng); - + if (mfmsr() & MSR_DR) { + rng = get_cpu_var(pnv_rng); + *v = rng_whiten(rng, in_be64(rng->regs)); + put_cpu_var(rng); + } else { + rng = raw_cpu_read(pnv_rng); + *v = rng_whiten(rng, __raw_rm_readq(rng->regs_real)); + } return 1; } EXPORT_SYMBOL_GPL(pnv_get_random_long); -- 2.35.1