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 4F3CCF483DE for ; Mon, 23 Mar 2026 17:47:04 +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: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:In-Reply-To:References:List-Owner; bh=Ocw65/pV/F3VkulhvpJVvk0PeG4d8waPMt+IQekoqB8=; b=2ASvJyJOyVZ++q7QAzmxJh/Wul MrpHWDLi1ReyyedDYfpLNFnmkmlHPP2NvmcYtya6FE8p12rfDgwEjR0IRUHz+Gh5jIKLdZYHNemfr bpKFnohS4cyReu72BmQoeA4e0UbJ6te9dbSB2mFQqBGSpGhXh+pnR88DuH20Th6Nq5FCTbZ43+7aK FT8cyhsOjFsT9DqLdZMNWykxAmQkCVYbdn0coc11urREhxCgpCldI93gV0U4Rqflpex4ysS8RLOtM 2UMzhAQPzn9r7XGIlzu4qK4N+Lisksem4z6uGyTYRb34eMl+8Ua/RrZHyfPwUL6evty08ZejxNvlh U4s9B13w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w4jMi-0000000HFxM-30ew; Mon, 23 Mar 2026 17:47:00 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1w4jMg-0000000HFvd-30Qs for linux-arm-kernel@lists.infradead.org; Mon, 23 Mar 2026 17:46:59 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 5531A436F8; Mon, 23 Mar 2026 17:46:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F0B9C2BC9E; Mon, 23 Mar 2026 17:46:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774288018; bh=cyADZ9NAmmVw6DXEt8XTqLzsSVTUO02DgLX3MND3plw=; h=From:To:Cc:Subject:Date:From; b=UAMvzguFqw7l8E04akXR2DAi3tC8rDn/FLDt8xxkmA5qEwlx5ozAhlENGBr7/S3i/ aYOJ8zGdC/h0L8WXB3NXAuPY+hEzl4QRSDoDBSchHroyMJgNiJkdrOjj1G+jM9EMlb d/9hF5mj0cE17Znj5CirDtDv+QEGcyTd5DE91O0t1rJaRhweKOD3O5T58Flwbckugc gX58KagYf7SdYdLlpZ+u9boMPzMwxrmzWykD/deksMIWj58MRCosnvSon72JyMXLGa uYZTkvK4SSBwcpWt3HqmTsgQopRWSxpqpGkhc30Em6T8br9SxT1mHxPW1huBsqGRnR hogx5xAFoQ0Nw== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1w4jMe-00000004pwY-06KE; Mon, 23 Mar 2026 17:46:56 +0000 From: Marc Zyngier To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: Joey Gouly , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Mark Brown Subject: [PATCH] KVM: arm64: set_id_regs: Allow GICv3 support to be set at runtime Date: Mon, 23 Mar 2026 17:46:42 +0000 Message-ID: <20260323174642.3183075-1-maz@kernel.org> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, joey.gouly@arm.com, suzuki.poulose@arm.com, oupton@kernel.org, yuzenghui@huawei.com, broonie@kernel.org 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-20260323_104658_818835_EDF97740 X-CRM114-Status: GOOD ( 19.40 ) 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 set_id_regs creates a GIC3 guest when possible, and then proceeds to write the ID registers as if they were not affected by the presence of a GIC. As it turns out, ID_AA64PFR1_EL1 is the proof of the contrary. KVM now makes a point in exposing the GIC support to the guest, no matter what userspace says (userspace such as QEMU is known to write silly things at times). Accommodate for this level of nonsense by teaching set_id_regs about fields that are mutable, and only compare registers that have been re-sanitised first. Reported-by: Mark Brown Signed-off-by: Marc Zyngier --- .../testing/selftests/kvm/arm64/set_id_regs.c | 52 ++++++++++++++++--- 1 file changed, 45 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/kvm/arm64/set_id_regs.c b/tools/testing/selftests/kvm/arm64/set_id_regs.c index 73de5be58bab0..24f70312b3557 100644 --- a/tools/testing/selftests/kvm/arm64/set_id_regs.c +++ b/tools/testing/selftests/kvm/arm64/set_id_regs.c @@ -37,6 +37,9 @@ struct reg_ftr_bits { * For FTR_LOWER_SAFE, safe_val is used as the minimal safe value. */ int64_t safe_val; + + /* Allowed to be changed by the host after run */ + bool mutable; }; struct test_feature_reg { @@ -44,7 +47,7 @@ struct test_feature_reg { const struct reg_ftr_bits *ftr_bits; }; -#define __REG_FTR_BITS(NAME, SIGNED, TYPE, SHIFT, MASK, SAFE_VAL) \ +#define __REG_FTR_BITS(NAME, SIGNED, TYPE, SHIFT, MASK, SAFE_VAL, MUT) \ { \ .name = #NAME, \ .sign = SIGNED, \ @@ -52,15 +55,20 @@ struct test_feature_reg { .shift = SHIFT, \ .mask = MASK, \ .safe_val = SAFE_VAL, \ + .mutable = MUT, \ } #define REG_FTR_BITS(type, reg, field, safe_val) \ __REG_FTR_BITS(reg##_##field, FTR_UNSIGNED, type, reg##_##field##_SHIFT, \ - reg##_##field##_MASK, safe_val) + reg##_##field##_MASK, safe_val, false) + +#define REG_FTR_BITS_MUTABLE(type, reg, field, safe_val) \ + __REG_FTR_BITS(reg##_##field, FTR_UNSIGNED, type, reg##_##field##_SHIFT, \ + reg##_##field##_MASK, safe_val, true) #define S_REG_FTR_BITS(type, reg, field, safe_val) \ __REG_FTR_BITS(reg##_##field, FTR_SIGNED, type, reg##_##field##_SHIFT, \ - reg##_##field##_MASK, safe_val) + reg##_##field##_MASK, safe_val, false) #define REG_FTR_END \ { \ @@ -134,7 +142,8 @@ static const struct reg_ftr_bits ftr_id_aa64pfr0_el1[] = { REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64PFR0_EL1, CSV2, 0), REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64PFR0_EL1, DIT, 0), REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64PFR0_EL1, SEL2, 0), - REG_FTR_BITS(FTR_EXACT, ID_AA64PFR0_EL1, GIC, 0), + /* GICv3 support will be forced at run time if available */ + REG_FTR_BITS_MUTABLE(FTR_EXACT, ID_AA64PFR0_EL1, GIC, 0), REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64PFR0_EL1, EL3, 1), REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64PFR0_EL1, EL2, 1), REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64PFR0_EL1, EL1, 1), @@ -634,12 +643,38 @@ static void test_user_set_mte_reg(struct kvm_vcpu *vcpu) ksft_test_result_pass("ID_AA64PFR1_EL1.MTE_frac no longer 0xF\n"); } +static uint64_t reset_mutable_bits(uint32_t id, uint64_t val) +{ + struct test_feature_reg *reg = NULL; + + for (int i = 0; i < ARRAY_SIZE(test_regs); i++) { + if (test_regs[i].reg == id) { + reg = &test_regs[i]; + break; + } + } + + if (!reg) + return val; + + for (const struct reg_ftr_bits *bits = reg->ftr_bits; bits->type != FTR_END; bits++) { + if (bits->mutable) { + val &= ~bits->mask; + val |= bits->safe_val << bits->shift; + } + } + + return val; +} + static void test_guest_reg_read(struct kvm_vcpu *vcpu) { bool done = false; struct ucall uc; while (!done) { + uint64_t val; + vcpu_run(vcpu); switch (get_ucall(vcpu, &uc)) { @@ -647,9 +682,11 @@ static void test_guest_reg_read(struct kvm_vcpu *vcpu) REPORT_GUEST_ASSERT(uc); break; case UCALL_SYNC: + val = test_reg_vals[encoding_to_range_idx(uc.args[2])]; + val = reset_mutable_bits(uc.args[2], val); + /* Make sure the written values are seen by guest */ - TEST_ASSERT_EQ(test_reg_vals[encoding_to_range_idx(uc.args[2])], - uc.args[3]); + TEST_ASSERT_EQ(val, reset_mutable_bits(uc.args[2], uc.args[3])); break; case UCALL_DONE: done = true; @@ -740,7 +777,8 @@ static void test_assert_id_reg_unchanged(struct kvm_vcpu *vcpu, uint32_t encodin uint64_t observed; observed = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(encoding)); - TEST_ASSERT_EQ(test_reg_vals[idx], observed); + TEST_ASSERT_EQ(reset_mutable_bits(test_reg_vals[idx], encoding), + reset_mutable_bits(observed, encoding)); } static void test_reset_preserves_id_regs(struct kvm_vcpu *vcpu) -- 2.47.3