From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-83.mta0.migadu.com [91.218.175.83]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 03D8649EC4D for ; Mon, 31 Aug 2026 16:34:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.83 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788194084; cv=none; b=jSMUp9MPVK7jZ4Xqu6OCS7YRg+LMTt0FX/LKvG4/xDYSWpx1gH9pJDndsHBLEzBV/QRCwcwmBmE4Mq47HV53NCHTVrxSEEQnOxrAvWpdDicwUGf8iZOrwnZuMcmpVdanR7nojk3OTA3zuKqZ+n5KhKx4BRzstV99SkBeRqnEf2M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788194084; c=relaxed/simple; bh=2sbto41tBk300tVzgzcERGaOKg9olZAVUAA+XHNTpvk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=QQYPtPCdDtRyMoPyzU0ITa4TPSrqgkxjEK2lmxFbVm1YbSai9PEKbAOudY7OidXOmgWGay73e334wwMBwbAfrMIaOKVIf5jC8Z0aOzwQV+WQSzQJRuVcde2Q5YzcrE8cxKDI+eLr1CEIkmWrp7y+0mnzA8nLpIz/Z9aOYx0xMO0= 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=JnfKgDgO; arc=none smtp.client-ip=91.218.175.83 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="JnfKgDgO" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=2sbto41tBk300tVzgzcERGaOKg9olZAVUAA+XHNTpvk=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788194080; v=1; x=1788798880; b=JnfKgDgOy7sepHNRkXUMQcVjDb6eTxmR/OcA10Gr3plpf7Jo5aCZMFmFEKxJx6UGAm9eHSie 4318OCxDGxN/wiDqgoamY40xpZZud98D0D0FAu7VVKOJrnfquaQvelzwsuowm2NxvCEbu0ojxkm 3TZZ8+TF21WbFQhxJaz8Mm4I= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id a1d3c5d0688f5f6d; Mon, 31 Aug 2026 16:34:40 +0000 X-Mizu-Trace-ID: a1d3c5d0688f5f6d X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Will Deacon , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Vincent Donnefort , Quentin Perret , Fuad Tabba Subject: [PATCH 06/17] KVM: arm64: Add {flush,sync}_hyp_timer_state() primitives Date: Mon, 31 Aug 2026 17:34:10 +0100 Message-Id: <20260831163421.272420-7-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260831163421.272420-1-fuad.tabba@linux.dev> References: <20260831163421.272420-1-fuad.tabba@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Marc Zyngier A protected guest's virtual timer is programmed from EL2's own copy of the state and read back there, so the host cannot change the guest's deadline. cntvoff_el2 is zeroed, so the guest's virtual time is the physical time. The flush also preserves the guest's CNTV and CNTP CVAL/CTL across the host's full-context copy into the hyp vCPU. Signed-off-by: Marc Zyngier Co-developed-by: Fuad Tabba Signed-off-by: Fuad Tabba --- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 39 ++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 14e847b122abf..d4b0f69ff130c 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -154,6 +154,33 @@ static void sync_hyp_vgic_state(struct pkvm_hyp_vcpu *hyp_vcpu) host_cpu_if->vgic_lr[i] = hyp_cpu_if->vgic_lr[i]; } +static void flush_hyp_timer_state(struct pkvm_hyp_vcpu *hyp_vcpu) +{ + if (!pkvm_hyp_vcpu_is_protected(hyp_vcpu)) + return; + + /* A hyp vcpu has no offset, and sees vtime == ptime. */ + write_sysreg(0, cntvoff_el2); + write_sysreg_el0(__vcpu_sys_reg(&hyp_vcpu->vcpu, CNTV_CVAL_EL0), + SYS_CNTV_CVAL); + isb(); + write_sysreg_el0(__vcpu_sys_reg(&hyp_vcpu->vcpu, CNTV_CTL_EL0), + SYS_CNTV_CTL); +} + +static void sync_hyp_timer_state(struct pkvm_hyp_vcpu *hyp_vcpu) +{ + if (!pkvm_hyp_vcpu_is_protected(hyp_vcpu)) + return; + + /* + * Preserve the vtimer state so that it is always correct, + * even if the host tries to make a mess. + */ + __vcpu_assign_sys_reg(&hyp_vcpu->vcpu, CNTV_CVAL_EL0, read_sysreg_el0(SYS_CNTV_CVAL)); + __vcpu_assign_sys_reg(&hyp_vcpu->vcpu, CNTV_CTL_EL0, read_sysreg_el0(SYS_CNTV_CTL)); +} + static void __copy_vcpu_state(const struct kvm_vcpu *from_vcpu, struct kvm_vcpu *to_vcpu) { @@ -249,7 +276,17 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu) hyp_vcpu->vcpu.arch.iflags = host_vcpu->arch.iflags; flush_debug_state(hyp_vcpu); } else { + u64 v_cval = hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTV_CVAL_EL0]; + u64 v_ctl = hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTV_CTL_EL0]; + u64 p_cval = hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTP_CVAL_EL0]; + u64 p_ctl = hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTP_CTL_EL0]; + hyp_vcpu->vcpu.arch.ctxt = host_vcpu->arch.ctxt; + + hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTV_CVAL_EL0] = v_cval; + hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTV_CTL_EL0] = v_ctl; + hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTP_CVAL_EL0] = p_cval; + hyp_vcpu->vcpu.arch.ctxt.sys_regs[CNTP_CTL_EL0] = p_ctl; } /* __hyp_running_vcpu must be NULL in a guest context. */ @@ -264,6 +301,7 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu) hyp_vcpu->vcpu.arch.vsesr_el2 = host_vcpu->arch.vsesr_el2; flush_hyp_vgic_state(hyp_vcpu); + flush_hyp_timer_state(hyp_vcpu); hyp_vcpu->vcpu.arch.pid = host_vcpu->arch.pid; @@ -313,6 +351,7 @@ static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu, u32 exit_reason) host_vcpu->arch.hcr_el2 |= hyp_vcpu->vcpu.arch.hcr_el2 & HCR_VSE; sync_hyp_vgic_state(hyp_vcpu); + sync_hyp_timer_state(hyp_vcpu); hyp_vcpu->exit_code = exit_reason; } -- 2.39.5