From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3D77F19066B for ; Fri, 15 Nov 2024 22:49:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731710998; cv=none; b=qqaPNt46CVPwFfBj3zWd+G1U4UyuffN7H/sL4iUQRqBuYd/CwPRMZhrrDPODhIPAa01KNrIOZxVH+YNM2bmPhAumUhai0v+nS63Lqwi1NqVQkKVSlAfENLfYCt5nPH0Itt/C0qozE1Lutf7nasj/IlV4f+NTVoZq+YTgTykUqz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731710998; c=relaxed/simple; bh=r/SVrdbBU9SNgJo8YYPaL5QEFMLSpM22M4TcRutaIPU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=PZMv96AoQ5Y0qpm+zaZk4dOnxP/viiHLFLB/o67QQmwjQF/qEzbHucabZ3Hsrr2qcNbTOvM0I+AndvJDWmi2mH4467qaPHDLoZ4RLbxc426kqh7AJaWn6jlv1e1Ay0kLFR7Yv9a0VcjCWcCl48i5hd1JUNjJW0auz3gY/RsMRWo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=FhDSz8hI; arc=none smtp.client-ip=91.218.175.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="FhDSz8hI" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1731710994; 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=NQR6x+K8I3IG7YY483SZcp/bErB3loNnDH9ucbwLUUw=; b=FhDSz8hIiJhHxvgIixsJkAbEbmbqgzJ1EvIT4DKHeOX8lQhbdqSWK40fvxLykcjhC7b57n 349WcFkNg3K+19FDwlbgkwNmEfqXYIh0sMrhxcQtEdT4C8y2qAc5yCy7rgdZWSHvOtP84m Mb8w6oHN94HWQgkqFOB0T2du2R+PFsI= From: Oliver Upton To: kvmarm@lists.linux.dev Cc: Marc Zyngier , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Mingwei Zhang , Colton Lewis , Alexandru Elisei , Oliver Upton Subject: [PATCH v2 05/16] KVM: arm64: Evaluate debug owner at vcpu_load() Date: Fri, 15 Nov 2024 14:49:13 -0800 Message-Id: <20241115224924.2132364-6-oliver.upton@linux.dev> In-Reply-To: <20241115224924.2132364-1-oliver.upton@linux.dev> References: <20241115224924.2132364-1-oliver.upton@linux.dev> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT In preparation for tossing the debug_ptr mess, introduce an enumeration to track the ownership of the debug registers while in the guest. Update the owner at vcpu_load() based on whether the host needs to steal the guest's debug context or if breakpoints/watchpoints are actively in use. Signed-off-by: Oliver Upton --- arch/arm64/include/asm/kvm_host.h | 11 ++++++++ arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/debug.c | 47 +++++++++++++++++++++++++++++++ arch/arm64/kvm/sys_regs.c | 2 ++ 4 files changed, 61 insertions(+) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 1ec025181de0..d2e4c33427bf 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -756,6 +756,12 @@ struct kvm_vcpu_arch { struct kvm_guest_debug_arch vcpu_debug_state; struct kvm_guest_debug_arch external_debug_state; + enum { + VCPU_DEBUG_FREE, + VCPU_DEBUG_HOST_OWNED, + VCPU_DEBUG_GUEST_OWNED, + } debug_owner; + /* VGIC state */ struct vgic_cpu vgic_cpu; struct arch_timer_cpu timer_cpu; @@ -1345,10 +1351,15 @@ void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu); void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); +void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu); +void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu); #define kvm_vcpu_os_lock_enabled(vcpu) \ (!!(__vcpu_sys_reg(vcpu, OSLSR_EL1) & OSLSR_EL1_OSLK)) +#define kvm_host_owns_debug_regs(vcpu) \ + ((vcpu)->arch.debug_owner == VCPU_DEBUG_HOST_OWNED) + int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu, diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 3822774840e1..a068337da52a 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -598,6 +598,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) kvm_vgic_load(vcpu); kvm_timer_vcpu_load(vcpu); + kvm_vcpu_load_debug(vcpu); if (has_vhe()) kvm_vcpu_load_vhe(vcpu); kvm_arch_vcpu_load_fp(vcpu); diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 1ee2fd765b62..da297cc92ed5 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -313,3 +313,50 @@ void kvm_init_host_debug_data(void) !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P)) host_data_set_flag(HAS_TRBE); } + +void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu) +{ + u64 mdscr; + + /* Must be called before kvm_vcpu_load_vhe() */ + KVM_BUG_ON(vcpu_get_flag(vcpu, SYSREGS_ON_CPU), vcpu->kvm); + + /* + * Determine which of the possible debug states we're in: + * + * - VCPU_DEBUG_HOST_OWNED: KVM has taken ownership of the guest's + * breakpoint/watchpoint registers, or needs to use MDSCR_EL1 to do + * software step or emulate the effects of the OS Lock being enabled. + * + * - VCPU_DEBUG_GUEST_OWNED: The guest has debug exceptions enabled, and + * the breakpoint/watchpoint registers need to be loaded eagerly. + * + * - VCPU_DEBUG_FREE: Neither of the above apply, no breakpoint/watchpoint + * context needs to be loaded on the CPU. + */ + if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) { + vcpu->arch.debug_owner = VCPU_DEBUG_HOST_OWNED; + } else { + mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); + + if (mdscr & (MDSCR_EL1_KDE | MDSCR_EL1_MDE)) + vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED; + else + vcpu->arch.debug_owner = VCPU_DEBUG_FREE; + } +} + +/* + * Updates ownership of the debug registers after a trapped guest access to a + * breakpoint/watchpoint register. Host ownership of the debug registers is of + * strictly higher priority, and it is the responsibility of the VMM to emulate + * guest debug exceptions in this configuration. + */ +void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu) +{ + if (kvm_host_owns_debug_regs(vcpu)) + return; + + WARN_ON_ONCE(vcpu->arch.debug_owner == VCPU_DEBUG_GUEST_OWNED); + vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED; +} diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 83c6b4a07ef5..b17cd93c1c8d 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -656,6 +656,7 @@ static bool trap_debug_regs(struct kvm_vcpu *vcpu, if (p->is_write) vcpu_set_flag(vcpu, DEBUG_DIRTY); + kvm_debug_set_guest_ownership(vcpu); trace_trap_reg(__func__, r->reg, p->is_write, p->regval); return true; @@ -709,6 +710,7 @@ static bool trap_bvr(struct kvm_vcpu *vcpu, else dbg_to_reg(vcpu, p, rd, dbg_reg); + kvm_debug_set_guest_ownership(vcpu); trace_trap_reg(__func__, rd->CRm, p->is_write, *dbg_reg); return true; -- 2.39.5