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 AD11DC61DC4 for ; Thu, 27 Aug 2026 21:12:53 +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:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=Q0WNsi8vEOZeo9klF/ETWu9k5gas7L2GKrQ51Cba27k=; b=n0qdzA/eIOeKBA XiHVMesfXgwTRqCnlNEzmPnEZbnpC9OVovVWXGJdYb7YwmUvJGwEJwPr1ExiZAOMQScG4uWpME9YR GHrs2MlSJp1SGdVrjql0ZwM6GFlfgUWjbDoIr+CXg7xzmo/S6hKkC13LXvVsBpAOleuHcvuryUXPU pTRZvZSvREKBrIPLu4smCUBPKMSlfKYpu9HSjthCJbElfBBjigQeM0W4zG4MZyl20OhUIFXZapbm7 U2+Csgl/dIKrOxNSqVcqFTl8gFDpE39gXQcI4cOzKxmheE/+9zN6BObfWxuynuvsqKZUWDgxPGxhl KFHnbG/hlrlJUI0YG+1g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wzhOa-00000004nDw-2D0p; Thu, 27 Aug 2026 21:12:24 +0000 Received: from buffalo.birch.relay.mailchannels.net ([23.83.209.24]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wzhOX-00000004nDO-1nTm; Thu, 27 Aug 2026 21:12:22 +0000 X-Sender-Id: dreamhost|x-authsender|dave@stgolabs.net Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id 63154641C90; Thu, 27 Aug 2026 21:12:18 +0000 (UTC) Received: from pdx1-sub0-mail-a256.dreamhost.com (trex-green-6.trex.outbound.svc.cluster.local [100.96.173.63]) (Authenticated sender: dreamhost) by relay.mailchannels.net (Postfix) with ESMTPA id 03F0664185C; Thu, 27 Aug 2026 21:12:18 +0000 (UTC) X-Sender-Id: dreamhost|x-authsender|dave@stgolabs.net X-MC-Relay: Neutral X-MC-Copy: exfiltrated-credentials X-MailChannels-SenderId: dreamhost|x-authsender|dave@stgolabs.net X-MailChannels-Auth-Id: dreamhost X-Troubled-Celery: 28a404ec2d584dbe_1787865138234_1754118027 X-MC-Loop-Signature: 1787865138234:2965334719 X-MC-Ingress-Time: 1787865138234 Received: from pdx1-sub0-mail-a256.dreamhost.com (pop.dreamhost.com [64.90.62.162]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384) by 100.96.173.63 (trex/8.0.2); Thu, 27 Aug 2026 21:12:18 +0000 Received: from offworld.lan (unknown [76.167.199.67]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dave@stgolabs.net) by pdx1-sub0-mail-a256.dreamhost.com (Postfix) with ESMTPSA id 4hWDjs2lZGz1049; Thu, 27 Aug 2026 14:12:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=stgolabs.net; s=dreamhost; t=1787865137; bh=g3Bm4+9H5vp62O1EVPa150nZzSH2jKkHqCPDQBN1+5s=; h=From:To:Cc:Subject:Date:Content-Transfer-Encoding; b=mHdogV6TWPR/Ab+fq2zyWAkIrb+Aly1nP1rSlfoDJFp+LzjRpman4jrqe03IORaOc RAtAKMc3jR3mgUlaP5Zv3rxrc/kxfC2Zvpnl1xKH9t/46GMHsrsnqA5NwKNQ6ttsam k+LtCrJBs1blzbQrrBqeP1505XIVxom/g9iPw/5pC1P+M8/bnPsKR3AhzDfXNEOa9L NTvxXkxWbZMDyhF0V+vy1koEX8E2JyeFv1lXkgVgVgyTxZeh6fpWv6qpgXLoNcdDpd H6yjQ/BbWzqWQ5jHbvwB282TqenmwdKZ4g5AjbpgyiefzEdEZuGBwMkJ+UwDGhEmjg ROdUOPn0un4SA== From: Davidlohr Bueso To: anup@brainfault.org, atish.patra@linux.dev Cc: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, linux-riscv@lists.infradead.org, kvm-riscv@lists.infradead.org, Davidlohr Bueso Subject: [PATCH] riscv/kvm: Only context-switch senvcfg where it exists Date: Thu, 27 Aug 2026 14:12:09 -0700 Message-Id: <20260827211209.2871124-1-dave@stgolabs.net> X-Mailer: git-send-email 2.39.5 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260827_141221_595550_7E6B2239 X-CRM114-Status: UNSURE ( 6.94 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org senvcfg arrived in privileged spec 1.12, but H-capable cores on a 1.11 base exist, ie: sifive P500 (ESWIN EIC7700X) implements the hypervisor extension yet has no senvcfg. KVM swaps the CSR unconditionally on every vCPU entry, panicing the host upon a guest executing its first instruction: Oops - illegal instruction [#1] Modules linked in: kvm CPU: 2 UID: 0 PID: 127 Comm: qemu-system-ris Not tainted 7.2.0-kvm73bug+ #4 PREEMPTLAZY Hardware name: Unknown Unknown Product/Unknown Product, BIOS 2024.01 01/01/2024 epc : kvm_riscv_vcpu_enter_exit+0x26/0xcf8 [kvm] ra : kvm_arch_vcpu_ioctl_run+0x4ce/0x5a6 [kvm] status: 0000000200000100 badaddr: 0000000010a797f3 cause: 0000000000000002 [] kvm_riscv_vcpu_enter_exit+0x26/0xcf8 [kvm] [] kvm_arch_vcpu_ioctl_run+0x4ce/0x5a6 [kvm] [] kvm_vcpu_ioctl+0x180/0x5e4 [kvm] [] __riscv_sys_ioctl+0x84/0x9a [] do_trap_ecall_u+0x1d8/0x38a [] handle_exception+0x168/0x174 Code: 84aa 892e b703 8887 1773 1067 3023 16e5 b783 8907 (97f3) 10a7 Touch the CSR only when RISCV_ISA_EXT_XLINUXENVCFG is set, similar to __switch_to_envcfg() as well as other swaps conditional on their extentions. Fixes: db3c01c7a308 ("RISCV: KVM: Add senvcfg context save/restore") Signed-off-by: Davidlohr Bueso --- arch/riscv/kvm/vcpu.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index e062ca19f9d8..0c2d58db13ab 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -773,7 +773,8 @@ static __always_inline void kvm_riscv_vcpu_swap_in_guest_state(struct kvm_vcpu * struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr; vcpu->arch.host_scounteren = csr_swap(CSR_SCOUNTEREN, csr->scounteren); - vcpu->arch.host_senvcfg = csr_swap(CSR_SENVCFG, csr->senvcfg); + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_XLINUXENVCFG)) + vcpu->arch.host_senvcfg = csr_swap(CSR_SENVCFG, csr->senvcfg); if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN)) vcpu->arch.host_sstateen0 = csr_swap(CSR_SSTATEEN0, smcsr->sstateen0); if (riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICFISS)) @@ -787,7 +788,8 @@ static __always_inline void kvm_riscv_vcpu_swap_in_host_state(struct kvm_vcpu *v struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr; csr->scounteren = csr_swap(CSR_SCOUNTEREN, vcpu->arch.host_scounteren); - csr->senvcfg = csr_swap(CSR_SENVCFG, vcpu->arch.host_senvcfg); + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_XLINUXENVCFG)) + csr->senvcfg = csr_swap(CSR_SENVCFG, vcpu->arch.host_senvcfg); if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN)) smcsr->sstateen0 = csr_swap(CSR_SSTATEEN0, vcpu->arch.host_sstateen0); if (riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICFISS)) -- 2.39.5 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv