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AJvYcCV5AK+JCVBQbqTZtpo3xRchq6RsarZUIrxt7q/8/slA9xZtAccsXARYQj95n5x7eiK7u37Ne0A+5fv2YXKjmoU0QlR8SbyCkyH2DZO6 X-Gm-Message-State: AOJu0Yxfh5TkMgI97YJsoyNRxDcltPa0INMjfP9UJZRTgJL0lfirARR/ 7xBEM4nwQoklziMcez4WaTinl30b6UWgJ9YADrLT4h+Uq7JXJGzsOQOhnSCxmceY317/XepYQCQ m4w== X-Google-Smtp-Source: AGHT+IGXqcyVYyfsrhvREnbdq6WGI4rUGu/X6D5dsKbIh4G7tVICZ2/7A3biOpPmKuH5H/rOeO18jjJySrY= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a02:69a:b0:5f4:246c:1406 with SMTP id 41be03b00d2f7-6331ae42ab2mr99526a12.3.1715967604889; Fri, 17 May 2024 10:40:04 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 17 May 2024 10:38:48 -0700 In-Reply-To: <20240517173926.965351-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240517173926.965351-1-seanjc@google.com> X-Mailer: git-send-email 2.45.0.215.g3402c0e53f-goog Message-ID: <20240517173926.965351-12-seanjc@google.com> Subject: [PATCH v2 11/49] KVM: x86: Disallow KVM_CAP_X86_DISABLE_EXITS after vCPU creation From: Sean Christopherson To: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hou Wenlong , Kechen Lu , Oliver Upton , Maxim Levitsky , Binbin Wu , Yang Weijiang , Robert Hoo Content-Type: text/plain; charset="UTF-8" Reject KVM_CAP_X86_DISABLE_EXITS if vCPUs have been created, as disabling PAUSE/MWAIT/HLT exits after vCPUs have been created is broken and useless, e.g. except for PAUSE on SVM, the relevant intercepts aren't updated after vCPU creation. vCPUs may also end up with an inconsistent configuration if exits are disabled between creation of multiple vCPUs. Cc: Hou Wenlong Link: https://lore.kernel.org/all/9227068821b275ac547eb2ede09ec65d2281fe07.1680179693.git.houwenlong.hwl@antgroup.com Link: https://lore.kernel.org/all/20230121020738.2973-2-kechenl@nvidia.com Signed-off-by: Sean Christopherson --- Documentation/virt/kvm/api.rst | 1 + arch/x86/kvm/x86.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 6ab8b5b7c64e..884846282d06 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -7645,6 +7645,7 @@ branch to guests' 0x200 interrupt vector. :Architectures: x86 :Parameters: args[0] defines which exits are disabled :Returns: 0 on success, -EINVAL when args[0] contains invalid exits + or if any vCPUs have already been created Valid bits in args[0] are:: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bb34891d2f0a..4cb0c150a2f8 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6568,6 +6568,10 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, if (cap->args[0] & ~KVM_X86_DISABLE_VALID_EXITS) break; + mutex_lock(&kvm->lock); + if (kvm->created_vcpus) + goto disable_exits_unlock; + if (cap->args[0] & KVM_X86_DISABLE_EXITS_PAUSE) kvm->arch.pause_in_guest = true; @@ -6589,6 +6593,8 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, } r = 0; +disable_exits_unlock: + mutex_unlock(&kvm->lock); break; case KVM_CAP_MSR_PLATFORM_INFO: kvm->arch.guest_can_read_msr_platform_info = cap->args[0]; -- 2.45.0.215.g3402c0e53f-goog