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2017-10-18KVM: nVMX: update last_nonleaf_level when initializing nested EPTLadi Prosek1-0/+1
commit fd19d3b45164466a4adce7cbff448ba9189e1427 upstream. The function updates context->root_level but didn't call update_last_nonleaf_level so the previous and potentially wrong value was used for page walks. For example, a zero value of last_nonleaf_level would allow a potential out-of-bounds access in arch/x86/mmu/paging_tmpl.h's walk_addr_generic function (CVE-2017-12188). Fixes: 155a97a3d7c78b46cef6f1a973c831bc5a4f82bb Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-18KVM: nVMX: fix guest CR4 loading when emulating L2 to L1 exitHaozhong Zhang1-1/+1
commit 8eb3f87d903168bdbd1222776a6b1e281f50513e upstream. When KVM emulates an exit from L2 to L1, it loads L1 CR4 into the guest CR4. Before this CR4 loading, the guest CR4 refers to L2 CR4. Because these two CR4's are in different levels of guest, we should vmx_set_cr4() rather than kvm_set_cr4() here. The latter, which is used to handle guest writes to its CR4, checks the guest change to CR4 and may fail if the change is invalid. The failure may cause trouble. Consider we start a L1 guest with non-zero L1 PCID in use, (i.e. L1 CR4.PCIDE == 1 && L1 CR3.PCID != 0) and a L2 guest with L2 PCID disabled, (i.e. L2 CR4.PCIDE == 0) and following events may happen: 1. If kvm_set_cr4() is used in load_vmcs12_host_state() to load L1 CR4 into guest CR4 (in VMCS01) for L2 to L1 exit, it will fail because of PCID check. As a result, the guest CR4 recorded in L0 KVM (i.e. vcpu->arch.cr4) is left to the value of L2 CR4. 2. Later, if L1 attempts to change its CR4, e.g., clearing VMXE bit, kvm_set_cr4() in L0 KVM will think L1 also wants to enable PCID, because the wrong L2 CR4 is used by L0 KVM as L1 CR4. As L1 CR3.PCID != 0, L0 KVM will inject GP to L1 guest. Fixes: 4704d0befb072 ("KVM: nVMX: Exiting from L2 to L1") Cc: qemu-stable@nongnu.org Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-18KVM: MMU: always terminate page walks at level 1Ladi Prosek2-8/+9
commit 829ee279aed43faa5cb1e4d65c0cad52f2426c53 upstream. is_last_gpte() is not equivalent to the pseudo-code given in commit 6bb69c9b69c31 ("KVM: MMU: simplify last_pte_bitmap") because an incorrect value of last_nonleaf_level may override the result even if level == 1. It is critical for is_last_gpte() to return true on level == 1 to terminate page walks. Otherwise memory corruption may occur as level is used as an index to various data structures throughout the page walking code. Even though the actual bug would be wherever the MMU is initialized (as in the previous patch), be defensive and ensure here that is_last_gpte() returns the correct value. This patch is also enough to fix CVE-2017-12188. Fixes: 6bb69c9b69c315200ddc2bc79aee14c0184cf5b2 Cc: Andy Honig <ahonig@google.com> Signed-off-by: Ladi Prosek <lprosek@redhat.com> [Panic if walk_addr_generic gets an incorrect level; this is a serious bug and it's not worth a WARN_ON where the recovery path might hide further exploitable issues; suggested by Andrew Honig. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-12kvm/x86: Avoid async PF preempting the kernel incorrectlyBoqun Feng1-1/+1
commit a2b7861bb33b2538420bb5d8554153484d3f961f upstream. Currently, in PREEMPT_COUNT=n kernel, kvm_async_pf_task_wait() could call schedule() to reschedule in some cases. This could result in accidentally ending the current RCU read-side critical section early, causing random memory corruption in the guest, or otherwise preempting the currently running task inside between preempt_disable and preempt_enable. The difficulty to handle this well is because we don't know whether an async PF delivered in a preemptible section or RCU read-side critical section for PREEMPT_COUNT=n, since preempt_disable()/enable() and rcu_read_lock/unlock() are both no-ops in that case. To cure this, we treat any async PF interrupting a kernel context as one that cannot be preempted, preventing kvm_async_pf_task_wait() from choosing the schedule() path in that case. To do so, a second parameter for kvm_async_pf_task_wait() is introduced, so that we know whether it's called from a context interrupting the kernel, and the parameter is set properly in all the callsites. Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: VMX: use cmpxchg64Paolo Bonzini1-6/+6
commit c0a1666bcb2a33e84187a15eabdcd54056be9a97 upstream. This fixes a compilation failure on 32-bit systems. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: VMX: remove WARN_ON_ONCE in kvm_vcpu_trigger_posted_interruptHaozhong Zhang1-12/+21
commit 5753743fa5108b8f98bd61e40dc63f641b26c768 upstream. WARN_ON_ONCE(pi_test_sn(&vmx->pi_desc)) in kvm_vcpu_trigger_posted_interrupt() intends to detect the violation of invariant that VT-d PI notification event is not suppressed when vcpu is in the guest mode. Because the two checks for the target vcpu mode and the target suppress field cannot be performed atomically, the target vcpu mode may change in between. If that does happen, WARN_ON_ONCE() here may raise false alarms. As the previous patch fixed the real invariant breaker, remove this WARN_ON_ONCE() to avoid false alarms, and document the allowed cases instead. Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> Reported-by: "Ramamurthy, Venkatesh" <venkatesh.ramamurthy@intel.com> Reported-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Fixes: 28b835d60fcc ("KVM: Update Posted-Interrupts Descriptor when vCPU is preempted") Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: VMX: do not change SN bit in vmx_update_pi_irte()Haozhong Zhang1-5/+1
commit dc91f2eb1a4021eb6705c15e474942f84ab9b211 upstream. In kvm_vcpu_trigger_posted_interrupt() and pi_pre_block(), KVM assumes that PI notification events should not be suppressed when the target vCPU is not blocked. vmx_update_pi_irte() sets the SN field before changing an interrupt from posting to remapping, but it does not check the vCPU mode. Therefore, the change of SN field may break above the assumption. Besides, I don't see reasons to suppress notification events here, so remove the changes of SN field to avoid race condition. Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> Reported-by: "Ramamurthy, Venkatesh" <venkatesh.ramamurthy@intel.com> Reported-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Fixes: 28b835d60fcc ("KVM: Update Posted-Interrupts Descriptor when vCPU is preempted") Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05kvm: nVMX: Don't allow L2 to access the hardware CR8Jim Mattson1-0/+5
commit 51aa68e7d57e3217192d88ce90fd5b8ef29ec94f upstream. If L1 does not specify the "use TPR shadow" VM-execution control in vmcs12, then L0 must specify the "CR8-load exiting" and "CR8-store exiting" VM-execution controls in vmcs02. Failure to do so will give the L2 VM unrestricted read/write access to the hardware CR8. This fixes CVE-2017-12154. Signed-off-by: Jim Mattson <jmattson@google.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: VMX: Do not BUG() on out-of-bounds guest IRQJan H. Schönherr1-2/+7
commit 3a8b0677fc6180a467e26cc32ce6b0c09a32f9bb upstream. The value of the guest_irq argument to vmx_update_pi_irte() is ultimately coming from a KVM_IRQFD API call. Do not BUG() in vmx_update_pi_irte() if the value is out-of bounds. (Especially, since KVM as a whole seems to hang after that.) Instead, print a message only once if we find that we don't have a route for a certain IRQ (which can be out-of-bounds or within the array). This fixes CVE-2017-1000252. Fixes: efc644048ecde54 ("KVM: x86: Update IRTE for posted-interrupts") Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: nVMX: fix HOST_CR3/HOST_CR4 cacheLadi Prosek1-8/+8
commit 44889942b6eb356eab27ce25fe10701adfec7776 upstream. For nested virt we maintain multiple VMCS that can run on a vCPU. So it is incorrect to keep vmcs_host_cr3 and vmcs_host_cr4, whose purpose is caching the value of the rarely changing HOST_CR3 and HOST_CR4 VMCS fields, in vCPU-wide data structures. Hyper-V nested on KVM runs into this consistently for me with PCID enabled. CR3 is updated with a new value, unlikely(cr3 != vmx->host_state.vmcs_host_cr3) fires, and the currently loaded VMCS is updated. Then we switch from L2 to L1 and the next exit reverts CR3 to its old value. Fixes: d6e41f1151fe ("x86/mm, KVM: Teach KVM's VMX code that CR3 isn't a constant") Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: VMX: simplify and fix vmx_vcpu_pi_loadPaolo Bonzini1-33/+35
commit 31afb2ea2b10a7d17ce3db4cdb0a12b63b2fe08a upstream. The simplify part: do not touch pi_desc.nv, we can set it when the VCPU is first created. Likewise, pi_desc.sn is only handled by vmx_vcpu_pi_load, do not touch it in __pi_post_block. The fix part: do not check kvm_arch_has_assigned_device, instead check the SN bit to figure out whether vmx_vcpu_pi_put ran before. This matches what the previous patch did in pi_post_block. Cc: Huangweidong <weidong.huang@huawei.com> Cc: Gonglei <arei.gonglei@huawei.com> Cc: wangxin <wangxinxin.wang@huawei.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Tested-by: Longpeng (Mike) <longpeng2@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: VMX: avoid double list add with VT-d posted interruptsPaolo Bonzini1-37/+25
commit 8b306e2f3c41939ea528e6174c88cfbfff893ce1 upstream. In some cases, for example involving hot-unplug of assigned devices, pi_post_block can forget to remove the vCPU from the blocked_vcpu_list. When this happens, the next call to pi_pre_block corrupts the list. Fix this in two ways. First, check vcpu->pre_pcpu in pi_pre_block and WARN instead of adding the element twice in the list. Second, always do the list removal in pi_post_block if vcpu->pre_pcpu is set (not -1). The new code keeps interrupts disabled for the whole duration of pi_pre_block/pi_post_block. This is not strictly necessary, but easier to follow. For the same reason, PI.ON is checked only after the cmpxchg, and to handle it we just call the post-block code. This removes duplication of the list removal code. Cc: Huangweidong <weidong.huang@huawei.com> Cc: Gonglei <arei.gonglei@huawei.com> Cc: wangxin <wangxinxin.wang@huawei.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Tested-by: Longpeng (Mike) <longpeng2@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-05KVM: VMX: extract __pi_post_blockPaolo Bonzini1-33/+38
commit cd39e1176d320157831ce030b4c869bd2d5eb142 upstream. Simple code movement patch, preparing for the next one. Cc: Huangweidong <weidong.huang@huawei.com> Cc: Gonglei <arei.gonglei@huawei.com> Cc: wangxin <wangxinxin.wang@huawei.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Tested-by: Longpeng (Mike) <longpeng2@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-14KVM: SVM: Limit PFERR_NESTED_GUEST_PAGE error_code check to L1 guestBrijesh Singh1-1/+2
commit 64531a3b70b17c8d3e77f2e49e5e1bb70f571266 upstream. Commit 147277540bbc ("kvm: svm: Add support for additional SVM NPF error codes", 2016-11-23) added a new error code to aid nested page fault handling. The commit unprotects (kvm_mmu_unprotect_page) the page when we get a NPF due to guest page table walk where the page was marked RO. However, if an L0->L2 shadow nested page table can also be marked read-only when a page is read only in L1's nested page table. If such a page is accessed by L2 while walking page tables it can cause a nested page fault (page table walks are write accesses). However, after kvm_mmu_unprotect_page we may get another page fault, and again in an endless stream. To cover this use case, we qualify the new error_code check with vcpu->arch.mmu_direct_map so that the error_code check would run on L1 guest, and not the L2 guest. This avoids hitting the above scenario. Fixes: 147277540bbc54119172481c8ef6d930cc9fbfc2 Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Thomas Lendacky <thomas.lendacky@amd.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-01KVM: update to new mmu_notifier semantic v2Jérôme Glisse1-11/+0
Calls to mmu_notifier_invalidate_page() were replaced by calls to mmu_notifier_invalidate_range() and are now bracketed by calls to mmu_notifier_invalidate_range_start()/end() Remove now useless invalidate_page callback. Changed since v1 (Linus Torvalds) - remove now useless kvm_arch_mmu_notifier_invalidate_page() Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Tested-by: Mike Galbraith <efault@gmx.de> Tested-by: Adam Borowski <kilobyte@angband.pl> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: kvm@vger.kernel.org Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-25KVM, pkeys: do not use PKRU value in vcpu->arch.guest_fpu.statePaolo Bonzini1-3/+14
The host pkru is restored right after vcpu exit (commit 1be0e61), so KVM_GET_XSAVE will return the host PKRU value instead. Fix this by using the guest PKRU explicitly in fill_xsave and load_xsave. This part is based on a patch by Junkang Fu. The host PKRU data may also not match the value in vcpu->arch.guest_fpu.state, because it could have been changed by userspace since the last time it was saved, so skip loading it in kvm_load_guest_fpu. Reported-by: Junkang Fu <junkang.fjk@alibaba-inc.com> Cc: Yang Zhang <zy107165@alibaba-inc.com> Fixes: 1be0e61c1f255faaeab04a390e00c8b9b9042870 Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-08-25KVM: x86: simplify handling of PKRUPaolo Bonzini4-30/+9
Move it to struct kvm_arch_vcpu, replacing guest_pkru_valid with a simple comparison against the host value of the register. The write of PKRU in addition can be skipped if the guest has not enabled the feature. Once we do this, we need not test OSPKE in the host anymore, because guest_CR4.PKE=1 implies host_CR4.PKE=1. The static PKU test is kept to elide the code on older CPUs. Suggested-by: Yang Zhang <zy107165@alibaba-inc.com> Fixes: 1be0e61c1f255faaeab04a390e00c8b9b9042870 Cc: stable@vger.kernel.org Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-08-25KVM: x86: block guest protection keys unless the host has them enabledPaolo Bonzini1-1/+1
If the host has protection keys disabled, we cannot read and write the guest PKRU---RDPKRU and WRPKRU fail with #GP(0) if CR4.PKE=0. Block the PKU cpuid bit in that case. This ensures that guest_CR4.PKE=1 implies host_CR4.PKE=1. Fixes: 1be0e61c1f255faaeab04a390e00c8b9b9042870 Cc: stable@vger.kernel.org Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-08-11x86/cpufeature, kvm/svm: Rename (shorten) the new "virtualized ↵Borislav Petkov1-1/+1
VMSAVE/VMLOAD" CPUID flag "virtual_vmload_vmsave" is what is going to land in /proc/cpuinfo now as per v4.13-rc4, for a single feature bit which is clearly too long. So rename it to what it is called in the processor manual. "v_vmsave_vmload" is a bit shorter, after all. We could go more aggressively here but having it the same as in the processor manual is advantageous. Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Radim Krčmář <rkrcmar@redhat.com> Cc: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com> Cc: Jörg Rödel <joro@8bytes.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm-ML <kvm@vger.kernel.org> Link: http://lkml.kernel.org/r/20170801185552.GA3743@nazgul.tnic Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-03KVM: nVMX: Fix interrupt window request with "Acknowledge interrupt on exit"Wanpeng Li1-2/+9
------------[ cut here ]------------ WARNING: CPU: 5 PID: 2288 at arch/x86/kvm/vmx.c:11124 nested_vmx_vmexit+0xd64/0xd70 [kvm_intel] CPU: 5 PID: 2288 Comm: qemu-system-x86 Not tainted 4.13.0-rc2+ #7 RIP: 0010:nested_vmx_vmexit+0xd64/0xd70 [kvm_intel] Call Trace: vmx_check_nested_events+0x131/0x1f0 [kvm_intel] ? vmx_check_nested_events+0x131/0x1f0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x5dd/0x1be0 [kvm] ? vmx_vcpu_load+0x1be/0x220 [kvm_intel] ? kvm_arch_vcpu_load+0x62/0x230 [kvm] kvm_vcpu_ioctl+0x340/0x700 [kvm] ? kvm_vcpu_ioctl+0x340/0x700 [kvm] ? __fget+0xfc/0x210 do_vfs_ioctl+0xa4/0x6a0 ? __fget+0x11d/0x210 SyS_ioctl+0x79/0x90 do_syscall_64+0x8f/0x750 ? trace_hardirqs_on_thunk+0x1a/0x1c entry_SYSCALL64_slow_path+0x25/0x25 This can be reproduced by booting L1 guest w/ 'noapic' grub parameter, which means that tells the kernel to not make use of any IOAPICs that may be present in the system. Actually external_intr variable in nested_vmx_vmexit() is the req_int_win variable passed from vcpu_enter_guest() which means that the L0's userspace requests an irq window. I observed the scenario (!kvm_cpu_has_interrupt(vcpu) && L0's userspace reqeusts an irq window) is true, so there is no interrupt which L1 requires to inject to L2, we should not attempt to emualte "Acknowledge interrupt on exit" for the irq window requirement in this scenario. This patch fixes it by not attempt to emulate "Acknowledge interrupt on exit" if there is no L1 requirement to inject an interrupt to L2. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> [Added code comment to make it obvious that the behavior is not correct. We should do a userspace exit with open interrupt window instead of the nested VM exit. This patch still improves the behavior, so it was accepted as a (temporary) workaround.] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-08-02KVM: nVMX: mark vmcs12 pages dirty on L2 exitDavid Matlack1-10/+43
The host physical addresses of L1's Virtual APIC Page and Posted Interrupt descriptor are loaded into the VMCS02. The CPU may write to these pages via their host physical address while L2 is running, bypassing address-translation-based dirty tracking (e.g. EPT write protection). Mark them dirty on every exit from L2 to prevent them from getting out of sync with dirty tracking. Also mark the virtual APIC page and the posted interrupt descriptor dirty when KVM is virtualizing posted interrupt processing. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-08-02kvm: nVMX: don't flush VMCS12 during VMXOFF or VCPU teardownDavid Matlack1-5/+11
According to the Intel SDM, software cannot rely on the current VMCS to be coherent after a VMXOFF or shutdown. So this is a valid way to handle VMCS12 flushes. 24.11.1 Software Use of Virtual-Machine Control Structures ... If a logical processor leaves VMX operation, any VMCSs active on that logical processor may be corrupted (see below). To prevent such corruption of a VMCS that may be used either after a return to VMX operation or on another logical processor, software should execute VMCLEAR for that VMCS before executing the VMXOFF instruction or removing power from the processor (e.g., as part of a transition to the S3 and S4 power states). ... This fixes a "suspicious rcu_dereference_check() usage!" warning during kvm_vm_release() because nested_release_vmcs12() calls kvm_vcpu_write_guest_page() without holding kvm->srcu. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-08-02KVM: nVMX: do not pin the VMCS12Paolo Bonzini1-17/+7
Since the current implementation of VMCS12 does a memcpy in and out of guest memory, we do not need current_vmcs12 and current_vmcs12_page anymore. current_vmptr is enough to read and write the VMCS12. And David Matlack noted: This patch also fixes dirty tracking (memslot->dirty_bitmap) of the VMCS12 page by using kvm_write_guest. nested_release_page() only marks the struct page dirty. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> [Added David Matlack's note and nested_release_page_clean() fix.] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-08-02KVM: X86: init irq->level in kvm_pv_kick_cpu_opLongpeng(Mike)1-0/+1
'lapic_irq' is a local variable and its 'level' field isn't initialized, so 'level' is random, it doesn't matter but makes UBSAN unhappy: UBSAN: Undefined behaviour in .../lapic.c:... load of value 10 is not a valid value for type '_Bool' ... Call Trace: [<ffffffff81f030b6>] dump_stack+0x1e/0x20 [<ffffffff81f03173>] ubsan_epilogue+0x12/0x55 [<ffffffff81f03b96>] __ubsan_handle_load_invalid_value+0x118/0x162 [<ffffffffa1575173>] kvm_apic_set_irq+0xc3/0xf0 [kvm] [<ffffffffa1575b20>] kvm_irq_delivery_to_apic_fast+0x450/0x910 [kvm] [<ffffffffa15858ea>] kvm_irq_delivery_to_apic+0xfa/0x7a0 [kvm] [<ffffffffa1517f4e>] kvm_emulate_hypercall+0x62e/0x760 [kvm] [<ffffffffa113141a>] handle_vmcall+0x1a/0x30 [kvm_intel] [<ffffffffa114e592>] vmx_handle_exit+0x7a2/0x1fa0 [kvm_intel] ... Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-08-02KVM: X86: Fix loss of pending INIT due to raceWanpeng Li1-8/+11
When SMP VM start, AP may lost INIT because of receiving INIT between kvm_vcpu_ioctl_x86_get/set_vcpu_events. vcpu 0 vcpu 1 kvm_vcpu_ioctl_x86_get_vcpu_events events->smi.latched_init = 0 send INIT to vcpu1 set vcpu1's pending_events kvm_vcpu_ioctl_x86_set_vcpu_events if (events->smi.latched_init == 0) clear INIT in pending_events This patch fixes it by just update SMM related flags if we are in SMM. Thanks Peng Hao for the report and original commit message. Reported-by: Peng Hao <peng.hao2@zte.com.cn> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-08-01KVM: nVMX: fixes to nested virt interrupt injectionPaolo Bonzini2-25/+72
There are three issues in nested_vmx_check_exception: 1) it is not taking PFEC_MATCH/PFEC_MASK into account, as reported by Wanpeng Li; 2) it should rebuild the interruption info and exit qualification fields from scratch, as reported by Jim Mattson, because the values from the L2->L0 vmexit may be invalid (e.g. if an emulated instruction causes a page fault, the EPT misconfig's exit qualification is incorrect). 3) CR2 and DR6 should not be written for exception intercept vmexits (CR2 only for AMD). This patch fixes the first two and adds a comment about the last, outlining the fix. Cc: Jim Mattson <jmattson@google.com> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-08-01KVM: nVMX: do not fill vm_exit_intr_error_code in prepare_vmcs12Paolo Bonzini1-18/+34
Do this in the caller of nested_vmx_vmexit instead. nested_vmx_check_exception was doing a vmwrite to the vmcs02's VM_EXIT_INTR_ERROR_CODE field, so that prepare_vmcs12 would move the field to vmcs12->vm_exit_intr_error_code. However that isn't possible on pre-Haswell machines. Moving the vmcs12 write to the callers fixes it. Reported-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [Changed nested_vmx_reflect_vmexit() return type to (int)1 from (bool)1, thanks to fengguang.wu@intel.com] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-26KVM: LAPIC: Fix reentrancy issues with preempt notifiersWanpeng Li1-3/+14
Preempt can occur in the preemption timer expiration handler: CPU0 CPU1 preemption timer vmexit handle_preemption_timer(vCPU0) kvm_lapic_expired_hv_timer hv_timer_is_use == true sched_out sched_in kvm_arch_vcpu_load kvm_lapic_restart_hv_timer restart_apic_timer start_hv_timer already-expired timer or sw timer triggerd in the window start_sw_timer cancel_hv_timer /* back in kvm_lapic_expired_hv_timer */ cancel_hv_timer WARN_ON(!apic->lapic_timer.hv_timer_in_use); ==> Oops This can be reproduced if CONFIG_PREEMPT is enabled. ------------[ cut here ]------------ WARNING: CPU: 4 PID: 2972 at /home/kernel/linux/arch/x86/kvm//lapic.c:1563 kvm_lapic_expired_hv_timer+0x9e/0xb0 [kvm] CPU: 4 PID: 2972 Comm: qemu-system-x86 Tainted: G OE 4.13.0-rc2+ #16 RIP: 0010:kvm_lapic_expired_hv_timer+0x9e/0xb0 [kvm] Call Trace: handle_preemption_timer+0xe/0x20 [kvm_intel] vmx_handle_exit+0xb8/0xd70 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xdd1/0x1be0 [kvm] ? kvm_arch_vcpu_load+0x47/0x230 [kvm] ? kvm_arch_vcpu_load+0x62/0x230 [kvm] kvm_vcpu_ioctl+0x340/0x700 [kvm] ? kvm_vcpu_ioctl+0x340/0x700 [kvm] ? __fget+0xfc/0x210 do_vfs_ioctl+0xa4/0x6a0 ? __fget+0x11d/0x210 SyS_ioctl+0x79/0x90 do_syscall_64+0x81/0x220 entry_SYSCALL64_slow_path+0x25/0x25 ------------[ cut here ]------------ WARNING: CPU: 4 PID: 2972 at /home/kernel/linux/arch/x86/kvm//lapic.c:1498 cancel_hv_timer.isra.40+0x4f/0x60 [kvm] CPU: 4 PID: 2972 Comm: qemu-system-x86 Tainted: G W OE 4.13.0-rc2+ #16 RIP: 0010:cancel_hv_timer.isra.40+0x4f/0x60 [kvm] Call Trace: kvm_lapic_expired_hv_timer+0x3e/0xb0 [kvm] handle_preemption_timer+0xe/0x20 [kvm_intel] vmx_handle_exit+0xb8/0xd70 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xdd1/0x1be0 [kvm] ? kvm_arch_vcpu_load+0x47/0x230 [kvm] ? kvm_arch_vcpu_load+0x62/0x230 [kvm] kvm_vcpu_ioctl+0x340/0x700 [kvm] ? kvm_vcpu_ioctl+0x340/0x700 [kvm] ? __fget+0xfc/0x210 do_vfs_ioctl+0xa4/0x6a0 ? __fget+0x11d/0x210 SyS_ioctl+0x79/0x90 do_syscall_64+0x81/0x220 entry_SYSCALL64_slow_path+0x25/0x25 This patch fixes it by making the caller of cancel_hv_timer, start_hv_timer and start_sw_timer be in preemption-disabled regions, which trivially avoid any reentrancy issue with preempt notifier. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> [Add more WARNs. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-26KVM: nVMX: Fix loss of L2's NMI blocking stateWanpeng Li1-0/+2
Run kvm-unit-tests/eventinj.flat in L1 w/ ept=0 on both L0 and L1: Before NMI IRET test Sending NMI to self NMI isr running stack 0x461000 Sending nested NMI to self After nested NMI to self Nested NMI isr running rip=40038e After iret After NMI to self FAIL: NMI Commit 4c4a6f790ee862 (KVM: nVMX: track NMI blocking state separately for each VMCS) tracks NMI blocking state separately for vmcs01 and vmcs02. However it is not enough: - The L2 (kvm-unit-tests/eventinj.flat) generates NMI that will fault on IRET, so the L2 can generate #PF which can be intercepted by L0. - L0 walks L1's guest page table and sees the mapping is invalid, it resumes the L1 guest and injects the #PF into L1. At this point the vmcs02 has nmi_known_unmasked=true. - L1 sets set bit 3 (blocking by NMI) in the interruptibility-state field of vmcs12 (and fixes the shadow page table) before resuming L2 guest. - L1 executes VMRESUME to resume L2, causing a vmexit to L0 - during VMRESUME emulation, prepare_vmcs02 sets bit 3 in the interruptibility-state field of vmcs02, but nmi_known_unmasked is still true. - L2 immediately exits to L0 with another page fault, because L0 still has not updated the NGVA->HPA page tables. However, nmi_known_unmasked is true so vmx_recover_nmi_blocking does not do anything. The fix is to update nmi_known_unmasked when preparing vmcs02 from vmcs12. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-26KVM: nVMX: Fix posted intr delivery when vcpu is in guest modeWincy Van1-11/+11
The PI vector for L0 and L1 must be different. If dest vcpu0 is in guest mode while vcpu1 is delivering a non-nested PI to vcpu0, there wont't be any vmexit so that the non-nested interrupt will be delayed. Signed-off-by: Wincy Van <fanwenyi0529@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-26KVM: x86: do mask out upper bits of PAE CR3Paolo Bonzini1-2/+2
This reverts the change of commit f85c758dbee54cc3612a6e873ef7cecdb66ebee5, as the behavior it modified was intended. The VM is running in 32-bit PAE mode, and Table 4-7 of the Intel manual says: Table 4-7. Use of CR3 with PAE Paging Bit Position(s) Contents 4:0 Ignored 31:5 Physical address of the 32-Byte aligned page-directory-pointer table used for linear-address translation 63:32 Ignored (these bits exist only on processors supporting the Intel-64 architecture) To placate the static checker, write the mask explicitly as an unsigned long constant instead of using a 32-bit unsigned constant. Cc: Dan Carpenter <dan.carpenter@oracle.com> Fixes: f85c758dbee54cc3612a6e873ef7cecdb66ebee5 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-24KVM: VMX: remove unused fieldPaolo Bonzini1-1/+0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-20kvm: x86: hyperv: avoid livelock in oneshot SynIC timersRoman Kagan1-3/+4
If the SynIC timer message delivery fails due to SINT message slot being busy, there's no point to attempt starting the timer again until we're notified of the slot being released by the guest (via EOM or EOI). Even worse, when a oneshot timer fails to deliver its message, its re-arming with an expiration time in the past leads to immediate retry of the delivery, and so on, without ever letting the guest vcpu to run and release the slot, which results in a livelock. To avoid that, only start the timer when there's no timer message pending delivery. When there is, meaning the slot is busy, the processing will be restarted upon notification from the guest that the slot is released. Signed-off-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-20KVM: VMX: Fix invalid guest state detection after task-switch emulationWanpeng Li1-5/+10
This can be reproduced by EPT=1, unrestricted_guest=N, emulate_invalid_state=Y or EPT=0, the trace of kvm-unit-tests/taskswitch2.flat is like below, it tries to emulate invalid guest state task-switch: kvm_exit: reason TASK_SWITCH rip 0x0 info 40000058 0 kvm_emulate_insn: 42000:0:0f 0b (0x2) kvm_emulate_insn: 42000:0:0f 0b (0x2) failed kvm_inj_exception: #UD (0x0) kvm_entry: vcpu 0 kvm_exit: reason TASK_SWITCH rip 0x0 info 40000058 0 kvm_emulate_insn: 42000:0:0f 0b (0x2) kvm_emulate_insn: 42000:0:0f 0b (0x2) failed kvm_inj_exception: #UD (0x0) ...................... It appears that the task-switch emulation updates rflags (and vm86 flag) only after the segments are loaded, causing vmx->emulation_required to be set, when in fact invalid guest state emulation is not needed. This patch fixes it by updating vmx->emulation_required after the rflags (and vm86 flag) is updated in task-switch emulation. Thanks Radim for moving the update to vmx__set_flags and adding Paolo's suggestion for the check. Suggested-by: Nadav Amit <nadav.amit@gmail.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-19x86: add MULTIUSER dependency for KVMArnd Bergmann1-1/+1
KVM tries to select 'TASKSTATS', which had additional dependencies: warning: (KVM) selects TASKSTATS which has unmet direct dependencies (NET && MULTIUSER) Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-19KVM: nVMX: Disallow VM-entry in MOV-SS shadowJim Mattson1-0/+7
Immediately following MOV-to-SS/POP-to-SS, VM-entry is disallowed. This check comes after the check for a valid VMCS. When this check fails, the instruction pointer should fall through to the next instruction, the ALU flags should be set to indicate VMfailValid, and the VM-instruction error should be set to 26 ("VM entry with events blocked by MOV SS"). Signed-off-by: Jim Mattson <jmattson@google.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-19KVM: nVMX: track NMI blocking state separately for each VMCSPaolo Bonzini1-10/+14
vmx_recover_nmi_blocking is using a cached value of the guest interruptibility info, which is stored in vmx->nmi_known_unmasked. vmx_recover_nmi_blocking is run for both normal and nested guests, so the cached value must be per-VMCS. This fixes eventinj.flat in a nested non-EPT environment. With EPT it works, because the EPT violation handler doesn't have the vmx->nmi_known_unmasked optimization (it is unnecessary because, unlike vmx_recover_nmi_blocking, it can just look at the exit qualification). Thanks to Wanpeng Li for debugging the testcase and providing an initial patch. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-19KVM: x86: masking out upper bitsDan Carpenter1-2/+2
kvm_read_cr3() returns an unsigned long and gfn is a u64. We intended to mask out the bottom 5 bits but because of the type issue we mask the top 32 bits as well. I don't know if this is a real problem, but it causes static checker warnings. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-14kvm: x86: hyperv: make VP_INDEX managed by userspaceRoman Kagan3-19/+39
Hyper-V identifies vCPUs by Virtual Processor Index, which can be queried via HV_X64_MSR_VP_INDEX msr. It is defined by the spec as a sequential number which can't exceed the maximum number of vCPUs per VM. APIC ids can be sparse and thus aren't a valid replacement for VP indices. Current KVM uses its internal vcpu index as VP_INDEX. However, to make it predictable and persistent across VM migrations, the userspace has to control the value of VP_INDEX. This patch achieves that, by storing vp_index explicitly on vcpu, and allowing HV_X64_MSR_VP_INDEX to be set from the host side. For compatibility it's initialized to KVM vcpu index. Also a few variables are renamed to make clear distinction betweed this Hyper-V vp_index and KVM vcpu_id (== APIC id). Besides, a new capability, KVM_CAP_HYPERV_VP_INDEX, is added to allow the userspace to skip attempting msr writes where unsupported, to avoid spamming error logs. Signed-off-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-14KVM: async_pf: Let guest support delivery of async_pf from guest modeWanpeng Li3-4/+5
Adds another flag bit (bit 2) to MSR_KVM_ASYNC_PF_EN. If bit 2 is 1, async page faults are delivered to L1 as #PF vmexits; if bit 2 is 0, kvm_can_do_async_pf returns 0 if in guest mode. This is similar to what svm.c wanted to do all along, but it is only enabled for Linux as L1 hypervisor. Foreign hypervisors must never receive async page faults as vmexits, because they'd probably be very confused about that. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-14KVM: async_pf: Force a nested vmexit if the injected #PF is async_pfWanpeng Li3-10/+32
Add an nested_apf field to vcpu->arch.exception to identify an async page fault, and constructs the expected vm-exit information fields. Force a nested VM exit from nested_vmx_check_exception() if the injected #PF is async page fault. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-14KVM: async_pf: Add L1 guest async_pf #PF vmexit handlerWanpeng Li4-37/+50
This patch adds the L1 guest async page fault #PF vmexit handler, such by L1 similar to ordinary async page fault. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> [Passed insn parameters to kvm_mmu_page_fault().] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-14KVM: x86: Simplify kvm_x86_ops->queue_exception parameter listWanpeng Li3-10/+11
This patch removes all arguments except the first in kvm_x86_ops->queue_exception since they can extract the arguments from vcpu->arch.exception themselves. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-13kvm: x86: hyperv: add KVM_CAP_HYPERV_SYNIC2Roman Kagan3-6/+16
There is a flaw in the Hyper-V SynIC implementation in KVM: when message page or event flags page is enabled by setting the corresponding msr, KVM zeroes it out. This is problematic because on migration the corresponding MSRs are loaded on the destination, so the content of those pages is lost. This went unnoticed so far because the only user of those pages was in-KVM hyperv synic timers, which could continue working despite that zeroing. Newer QEMU uses those pages for Hyper-V VMBus implementation, and zeroing them breaks the migration. Besides, in newer QEMU the content of those pages is fully managed by QEMU, so zeroing them is undesirable even when writing the MSRs from the guest side. To support this new scheme, introduce a new capability, KVM_CAP_HYPERV_SYNIC2, which, when enabled, makes sure that the synic pages aren't zeroed out in KVM. Signed-off-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-13KVM: x86: make backwards_tsc_observed a per-VM variableLadi Prosek1-4/+2
The backwards_tsc_observed global introduced in commit 16a9602 is never reset to false. If a VM happens to be running while the host is suspended (a common source of the TSC jumping backwards), master clock will never be enabled again for any VM. In contrast, if no VM is running while the host is suspended, master clock is unaffected. This is inconsistent and unnecessarily strict. Let's track the backwards_tsc_observed variable separately and let each VM start with a clean slate. Real world impact: My Windows VMs get slower after my laptop undergoes a suspend/resume cycle. The only way to get the perf back is unloading and reloading the kvm module. Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-12KVM: SVM: Enable Virtual VMLOAD VMSAVE featureJanakarajan Natarajan1-0/+24
Enable the Virtual VMLOAD VMSAVE feature. This is done by setting bit 1 at position B8h in the vmcb. The processor must have nested paging enabled, be in 64-bit mode and have support for the Virtual VMLOAD VMSAVE feature for the bit to be set in the vmcb. Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-12KVM: SVM: Rename lbr_ctl field in the vmcb control areaJanakarajan Natarajan1-5/+5
Rename the lbr_ctl variable to better reflect the purpose of the field - provide support for virtualization extensions. Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-12KVM: SVM: Prepare for new bit definition in lbr_ctlJanakarajan Natarajan1-2/+2
The lbr_ctl variable in the vmcb control area is used to enable or disable Last Branch Record (LBR) virtualization. However, this is to be done using only bit 0 of the variable. To correct this and to prepare for a new feature, change the current usage to work only on a particular bit. Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-12KVM: SVM: handle singlestep exception when skipping emulated instructionsLadi Prosek1-26/+33
kvm_skip_emulated_instruction handles the singlestep debug exception which is something we almost always want. This commit (specifically the change in rdmsr_interception) makes the debug.flat KVM unit test pass on AMD. Two call sites still call skip_emulated_instruction directly: * In svm_queue_exception where it's used only for moving the rip forward * In task_switch_interception which is analogous to handle_task_switch in VMX Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-07-12KVM: x86: take slots_lock in kvm_free_pitRadim Krčmář1-0/+2
kvm_vm_release() did not have slots_lock when calling kvm_io_bus_unregister_dev() and this went unnoticed until 4a12f9517728 ("KVM: mark kvm->busses as rcu protected") added dynamic checks. Luckily, there should be no race at that point: ============================= WARNING: suspicious RCU usage 4.12.0.kvm+ #0 Not tainted ----------------------------- ./include/linux/kvm_host.h:479 suspicious rcu_dereference_check() usage! lockdep_rcu_suspicious+0xc5/0x100 kvm_io_bus_unregister_dev+0x173/0x190 [kvm] kvm_free_pit+0x28/0x80 [kvm] kvm_arch_sync_events+0x2d/0x30 [kvm] kvm_put_kvm+0xa7/0x2a0 [kvm] kvm_vm_release+0x21/0x30 [kvm] Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>