From patchwork Thu Jun 13 06:17:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 13696177 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 726F6C27C4F for ; Thu, 13 Jun 2024 06:18:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=h9krVENdXhuAHw4Sa5HDE8C/Kptnl3tGed/8Nff1MsE=; b=i+73668K9Yz+dU9wntI3o4ZQCp HhwqGsoSbsbdcmLZOkiROgEucKQD4UvSnhwq2aiLtfHVz5IJuGqt+fBTpZwDPA4fMCxrvn2282c85 9teGxs/NJ++hy6vjyZN3uaXvbxVHiGD2Gh6v9c1XYiNzIFpOt1K0IxVYJ50PGhihiY0PfG+oUis5E uejpuurgjCL6LIc3gs0K6HkWOncyt6SA7zDYvKG0uyvl1fYEBdZeHBzabcNlzBB3OwhSMyYsoJeii /IfCYuu9OGlOV8gomjG7HuBTXa8dhclJCLjPCS4D4fTfwy67FuNu8aIr6wMqrM7bOFa0H1vQ4TGEH j24hHgiw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sHdmf-0000000FH0s-1QyI; Thu, 13 Jun 2024 06:18:05 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sHdmb-0000000FGzW-3HcX for linux-arm-kernel@lists.infradead.org; Thu, 13 Jun 2024 06:18:03 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 657BA1063; Wed, 12 Jun 2024 23:18:23 -0700 (PDT) Received: from a077893.arm.com (unknown [10.163.44.128]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 71F4A3F5A1; Wed, 12 Jun 2024 23:17:52 -0700 (PDT) From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com Cc: Anshuman Khandual , Mark Brown , James Clark , Rob Herring , Marc Zyngier , Suzuki Poulose , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , linux-perf-users@vger.kernel.org, Oliver Upton , James Morse , kvmarm@lists.linux.dev Subject: [PATCH V18 2/9] KVM: arm64: Explicitly handle BRBE traps as UNDEFINED Date: Thu, 13 Jun 2024 11:47:24 +0530 Message-Id: <20240613061731.3109448-3-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240613061731.3109448-1-anshuman.khandual@arm.com> References: <20240613061731.3109448-1-anshuman.khandual@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240612_231801_920196_6FF78285 X-CRM114-Status: GOOD ( 17.15 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The Branch Record Buffer Extension (BRBE) adds a number of system registers and instructions, which we don't currently intend to expose to guests. Our existing logic handles this safely, but this could be improved with some explicit handling of BRBE. The presence of BRBE is currently hidden from guests as the cpufeature code's ftr_id_aa64dfr0[] table doesn't have an entry for the BRBE field, and so this will be zero in the sanitised value of ID_AA64DFR0 exposed to guests via read_sanitised_id_aa64dfr0_el1(). As the ftr_id_aa64dfr0[] table may gain an entry for the BRBE field in future, for robustness we should explicitly mask out the BRBE field in read_sanitised_id_aa64dfr0_el1(). The BRBE system registers and instructions are currently trapped by the existing configuration of the fine-grained traps. As neither the registers nor the instructions are described in the sys_reg_descs[] table, emulate_sys_reg() will warn that these are unknown before injecting an UNDEFINED exception into the guest. Well-behaved guests shouldn't try to use the registers or instructions, but badly-behaved guests could use these, resulting in unnecessary warnings. To avoid those warnings, we should explicitly handle the BRBE registers and instructions as UNDEFINED. Address the above by having read_sanitised_id_aa64dfr0_el1() mask out the ID_AA64DFR0.BRBE field, and explicitly handling all of the BRBE system registers and instructions as UNDEFINED. Cc: Marc Zyngier Cc: Oliver Upton Cc: James Morse Cc: Suzuki K Poulose Cc: Catalin Marinas Cc: Will Deacon Cc: kvmarm@lists.linux.dev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual ---- Changes in V18: - Updated the commit message arch/arm64/kvm/sys_regs.c | 56 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) Reviewed-by: Mark Rutland Reviewed-by: Mark Rutland --- arch/arm64/kvm/sys_regs.c | 56 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 22b45a15d068..3d4686abe5ee 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1304,6 +1304,11 @@ static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, return 0; } +#define BRB_INF_SRC_TGT_EL1(n) \ + { SYS_DESC(SYS_BRBINF_EL1(n)), undef_access }, \ + { SYS_DESC(SYS_BRBSRC_EL1(n)), undef_access }, \ + { SYS_DESC(SYS_BRBTGT_EL1(n)), undef_access } \ + /* Silly macro to expand the DBG{BCR,BVR,WVR,WCR}n_EL1 registers in one go */ #define DBG_BCR_BVR_WCR_WVR_EL1(n) \ { SYS_DESC(SYS_DBGBVRn_EL1(n)), \ @@ -1722,6 +1727,9 @@ static u64 read_sanitised_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, /* Hide SPE from guests */ val &= ~ID_AA64DFR0_EL1_PMSVer_MASK; + /* Hide BRBE from guests */ + val &= ~ID_AA64DFR0_EL1_BRBE_MASK; + return val; } @@ -2240,6 +2248,52 @@ static const struct sys_reg_desc sys_reg_descs[] = { { SYS_DESC(SYS_DBGCLAIMCLR_EL1), trap_raz_wi }, { SYS_DESC(SYS_DBGAUTHSTATUS_EL1), trap_dbgauthstatus_el1 }, + /* + * BRBE branch record sysreg address space is interleaved between + * corresponding BRBINF_EL1, BRBSRC_EL1, and BRBTGT_EL1. + */ + BRB_INF_SRC_TGT_EL1(0), + BRB_INF_SRC_TGT_EL1(16), + BRB_INF_SRC_TGT_EL1(1), + BRB_INF_SRC_TGT_EL1(17), + BRB_INF_SRC_TGT_EL1(2), + BRB_INF_SRC_TGT_EL1(18), + BRB_INF_SRC_TGT_EL1(3), + BRB_INF_SRC_TGT_EL1(19), + BRB_INF_SRC_TGT_EL1(4), + BRB_INF_SRC_TGT_EL1(20), + BRB_INF_SRC_TGT_EL1(5), + BRB_INF_SRC_TGT_EL1(21), + BRB_INF_SRC_TGT_EL1(6), + BRB_INF_SRC_TGT_EL1(22), + BRB_INF_SRC_TGT_EL1(7), + BRB_INF_SRC_TGT_EL1(23), + BRB_INF_SRC_TGT_EL1(8), + BRB_INF_SRC_TGT_EL1(24), + BRB_INF_SRC_TGT_EL1(9), + BRB_INF_SRC_TGT_EL1(25), + BRB_INF_SRC_TGT_EL1(10), + BRB_INF_SRC_TGT_EL1(26), + BRB_INF_SRC_TGT_EL1(11), + BRB_INF_SRC_TGT_EL1(27), + BRB_INF_SRC_TGT_EL1(12), + BRB_INF_SRC_TGT_EL1(28), + BRB_INF_SRC_TGT_EL1(13), + BRB_INF_SRC_TGT_EL1(29), + BRB_INF_SRC_TGT_EL1(14), + BRB_INF_SRC_TGT_EL1(30), + BRB_INF_SRC_TGT_EL1(15), + BRB_INF_SRC_TGT_EL1(31), + + /* Remaining BRBE sysreg addresses space */ + { SYS_DESC(SYS_BRBCR_EL1), undef_access }, + { SYS_DESC(SYS_BRBFCR_EL1), undef_access }, + { SYS_DESC(SYS_BRBTS_EL1), undef_access }, + { SYS_DESC(SYS_BRBINFINJ_EL1), undef_access }, + { SYS_DESC(SYS_BRBSRCINJ_EL1), undef_access }, + { SYS_DESC(SYS_BRBTGTINJ_EL1), undef_access }, + { SYS_DESC(SYS_BRBIDR0_EL1), undef_access }, + { SYS_DESC(SYS_MDCCSR_EL0), trap_raz_wi }, { SYS_DESC(SYS_DBGDTR_EL0), trap_raz_wi }, // DBGDTR[TR]X_EL0 share the same encoding @@ -2751,6 +2805,8 @@ static struct sys_reg_desc sys_insn_descs[] = { { SYS_DESC(SYS_DC_CISW), access_dcsw }, { SYS_DESC(SYS_DC_CIGSW), access_dcgsw }, { SYS_DESC(SYS_DC_CIGDSW), access_dcgsw }, + { SYS_DESC(OP_BRB_IALL), undef_access }, + { SYS_DESC(OP_BRB_INJ), undef_access }, }; static const struct sys_reg_desc *first_idreg;