From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 B9B37D2FB for ; Thu, 20 Feb 2025 01:07:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740013681; cv=none; b=g35Qk4Kin6rihEk+yqKnOLwxanvzIsCW6iGDpjPmbrEjU0NcvmtrpQWgQ+magOD484F/80CcKRl6hmTzxPNVNmzDysvAvrq0gXHN40auSGISmWExTCpTYNwt1xZyq24xz7l3BdxeWmkzdt53JzatGRSg2GJLNbygKYRY8BVMc7U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740013681; c=relaxed/simple; bh=/lGakXVZCQx0lc7hrdwMSme41IJ7zwDg4c/s5KFisuE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Content-Type; b=TpxWyOLSJ7Qm6VkS3uNS3XsWO2re6tuAbkY8iBWfdyRJMwQH/6KI4kpuaRlbxQ1t9C6XdDRMBXxvzDpY4aZPL0QJlcgPgr7oOhhbQGFlVzdc01+67E/kE/jD32ySL4UBlJgRx4lMkQsALWeVb9Y2sOkPGfZ5bk7ZWv8aDXCvtvw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=ONW2FNuB; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ONW2FNuB" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-220e62c4f27so9414125ad.0 for ; Wed, 19 Feb 2025 17:07:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740013679; x=1740618479; darn=vger.kernel.org; h=to:from:subject:message-id:references:mime-version:in-reply-to:date :from:to:cc:subject:date:message-id:reply-to; bh=3V15TKwqZAC8dpBd3zv+ePQ+zbQqk14dXCyWdHzdLQE=; b=ONW2FNuBoUMpZHvR6P1JiHRGrfNz5oKpcuEoTiC+KVc7yz/BLZJqFsJPY9b140ea2S QyUJyeNGAHlWPvoPGPPXjpMrNsiKs47j1TtM/uyJdQkC+7l5y/aNqAy7wL7H0qanUI2P i5VWE8ml6IamonGn6ZyzKuPTLr+S9wvi8JNoqaBPFsJOGxHEv6OSxr/ldQrTeqJVM6ym gN/mSlstgHGYL03mHreeq96HKvKy136hexEvB9Ir6guAWxv9TPNY7pNoywCZD/yEHsVB 6UepwPpasx8Zux9H18GOvvJaYeW/Lx4geQeg7J392eNbQCll8ygEgYHg35SM78N78wTK F8cg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740013679; x=1740618479; h=to:from:subject:message-id:references:mime-version:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=3V15TKwqZAC8dpBd3zv+ePQ+zbQqk14dXCyWdHzdLQE=; b=KGLJq/CV3Nfe82a++Dqe9rFIFNn82KHNQDUMxm9Jv1uBNNz03rYEb8MrPXMwKcMBaQ TxHuRNyEJq6wpyzXDLqrBexLBvuxsRTbijFwhAefvY5nb6jwPo/thzcebcWhxn9BVKL4 AYrAClDh2hPdHmioQoePdKkJJnBmhHqEIX31a3EtzmHB0A2q78XDhXk3lsjHt11CL9Nv UiWY5dB+K3qGRdKmG84M3S3NQsIFhQc4koz2YgeGqbfWvPxEuD7dsNpCJ7sVkYB3CKGh GkBWeP1zrowrxJHZ1VsgoFACcYihQxixkwmBxhwZWtL+bDH5Z/4QwFR1kVLE4f97f5ni 8XLQ== X-Forwarded-Encrypted: i=1; AJvYcCUcPoKZs5K9p25F9Wy2ur549fe/JHbYT5ObHqTr2P33RoQP3xU06wQ5Bh7FKeLdGM40O3loAV+OjTr1M80=@vger.kernel.org X-Gm-Message-State: AOJu0Yy4a/gO78U6SCZh/M3JBxUygfwIxnkAqUpn7cDX6Drg/CwyrxC6 mfG5y3D7xf4AKxyy+GMd/M2hLfmM2wv+Zp4+pP+BIasVPCKcnbxlJl/VQIWGofAr6s7q3VxiFBn 5ng== X-Google-Smtp-Source: AGHT+IFzBoJ9kkSVMGki9J8KCMzSJQurVwvUMLJQI9kOhy2xogXJenm8QqJIis7na1Vzj2miDdjT16wwdLc= X-Received: from pjbcz12.prod.google.com ([2002:a17:90a:d44c:b0:2fa:15aa:4d1e]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:ccc6:b0:220:ff3f:6cc9 with SMTP id d9443c01a7336-221711b98bbmr97110875ad.48.1740013679107; Wed, 19 Feb 2025 17:07:59 -0800 (PST) Date: Wed, 19 Feb 2025 17:07:57 -0800 In-Reply-To: <20250215010946.1201353-2-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250215010946.1201353-1-seanjc@google.com> <20250215010946.1201353-2-seanjc@google.com> Message-ID: Subject: Re: [PATCH 1/2] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the STI shadow From: Sean Christopherson To: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Doug Covelli Content-Type: text/plain; charset="us-ascii" On Fri, Feb 14, 2025, Sean Christopherson wrote: > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 7640a84e554a..fa0687711c48 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -4189,6 +4189,18 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in > > guest_state_enter_irqoff(); > > + /* > + * Set RFLAGS.IF prior to VMRUN, as the host's RFLAGS.IF at the time of > + * VMRUN controls whether or not physical IRQs are masked (KVM always > + * runs with V_INTR_MASKING_MASK). Toggle RFLAGS.IF here to avoid the > + * temptation to do STI+VMRUN+CLI, as AMD CPUs bleed the STI shadow > + * into guest state if delivery of an event during VMRUN triggers a > + * #VMEXIT, and the guest_state transitions already tell lockdep that > + * IRQs are being enabled/disabled. Note! GIF=0 for the entirety of > + * this path, so IRQs aren't actually unmasked while running host code. > + */ > + local_irq_enable(); Courtesy of the kernel test bot[*], these need to use the raw_ variants to avoid tracing. guest_state_{enter,exit}_irqoff() does all of the necessary tracing updates, so we should be good on that front. svm_vcpu_enter_exit+0x39: call to trace_hardirqs_on() leaves .noinstr.text section [*] https://lore.kernel.org/all/202502170739.2WX98OXk-lkp@intel.com > + > amd_clear_divider(); > > if (sev_es_guest(vcpu->kvm)) > @@ -4197,6 +4209,8 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in > else > __svm_vcpu_run(svm, spec_ctrl_intercepted); > > + local_irq_disable(); > + > guest_state_exit_irqoff(); > }