This is a note to let you know that I've just added the patch titled

KVM: nVMX: Fix mmu context after VMLAUNCH/VMRESUME failure

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kvm-nvmx-fix-mmu-context-after-vmlaunch-vmresume-failure.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Thu Feb 1 13:45:42 CET 2018

From: Wanpeng Li wanpeng.li@hotmail.com Date: Sun, 5 Nov 2017 16:54:49 -0800 Subject: KVM: nVMX: Fix mmu context after VMLAUNCH/VMRESUME failure

From: Wanpeng Li wanpeng.li@hotmail.com

[ Upstream commit 5af4157388adad82c339e3742fb6b67840721347 ]

Commit 4f350c6dbcb (kvm: nVMX: Handle deferred early VMLAUNCH/VMRESUME failure properly) can result in L1(run kvm-unit-tests/run_tests.sh vmx_controls in L1) null pointer deference and also L0 calltrace when EPT=0 on both L0 and L1.

In L1:

BUG: unable to handle kernel paging request at ffffffffc015bf8f IP: vmx_vcpu_run+0x202/0x510 [kvm_intel] PGD 146e13067 P4D 146e13067 PUD 146e15067 PMD 3d2686067 PTE 3d4af9161 Oops: 0003 [#1] PREEMPT SMP CPU: 2 PID: 1798 Comm: qemu-system-x86 Not tainted 4.14.0-rc4+ #6 RIP: 0010:vmx_vcpu_run+0x202/0x510 [kvm_intel] Call Trace: WARNING: kernel stack frame pointer at ffffb86f4988bc18 in qemu-system-x86:1798 has bad value 0000000000000002

In L0:

-----------[ cut here ]------------ WARNING: CPU: 6 PID: 4460 at /home/kernel/linux/arch/x86/kvm//vmx.c:9845 vmx_inject_page_fault_nested+0x130/0x140 [kvm_intel] CPU: 6 PID: 4460 Comm: qemu-system-x86 Tainted: G OE 4.14.0-rc7+ #25 RIP: 0010:vmx_inject_page_fault_nested+0x130/0x140 [kvm_intel] Call Trace: paging64_page_fault+0x500/0xde0 [kvm] ? paging32_gva_to_gpa_nested+0x120/0x120 [kvm] ? nonpaging_page_fault+0x3b0/0x3b0 [kvm] ? __asan_storeN+0x12/0x20 ? paging64_gva_to_gpa+0xb0/0x120 [kvm] ? paging64_walk_addr_generic+0x11a0/0x11a0 [kvm] ? lock_acquire+0x2c0/0x2c0 ? vmx_read_guest_seg_ar+0x97/0x100 [kvm_intel] ? vmx_get_segment+0x2a6/0x310 [kvm_intel] ? sched_clock+0x1f/0x30 ? check_chain_key+0x137/0x1e0 ? __lock_acquire+0x83c/0x2420 ? kvm_multiple_exception+0xf2/0x220 [kvm] ? debug_check_no_locks_freed+0x240/0x240 ? debug_smp_processor_id+0x17/0x20 ? __lock_is_held+0x9e/0x100 kvm_mmu_page_fault+0x90/0x180 [kvm] kvm_handle_page_fault+0x15c/0x310 [kvm] ? __lock_is_held+0x9e/0x100 handle_exception+0x3c7/0x4d0 [kvm_intel] vmx_handle_exit+0x103/0x1010 [kvm_intel] ? kvm_arch_vcpu_ioctl_run+0x1628/0x2e20 [kvm]

The commit avoids to load host state of vmcs12 as vmcs01's guest state since vmcs12 is not modified (except for the VM-instruction error field) if the checking of vmcs control area fails. However, the mmu context is switched to nested mmu in prepare_vmcs02() and it will not be reloaded since load_vmcs12_host_state() is skipped when nested VMLAUNCH/VMRESUME fails. This patch fixes it by reloading mmu context when nested VMLAUNCH/VMRESUME fails.

Reviewed-by: Jim Mattson jmattson@google.com Reviewed-by: Krish Sadhukhan krish.sadhukhan@oracle.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Radim Krčmář rkrcmar@redhat.com Cc: Jim Mattson jmattson@google.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 Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/vmx.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-)

--- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -11339,6 +11339,24 @@ static void prepare_vmcs12(struct kvm_vc kvm_clear_interrupt_queue(vcpu); }

+static void load_vmcs12_mmu_host_state(struct kvm_vcpu *vcpu, + struct vmcs12 *vmcs12) +{ + u32 entry_failure_code; + + nested_ept_uninit_mmu_context(vcpu); + + /* + * Only PDPTE load can fail as the value of cr3 was checked on entry and + * couldn't have changed. + */ + if (nested_vmx_load_cr3(vcpu, vmcs12->host_cr3, false, &entry_failure_code)) + nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_PDPTE_FAIL); + + if (!enable_ept) + vcpu->arch.walk_mmu->inject_page_fault = kvm_inject_page_fault; +} + /* * A part of what we need to when the nested L2 guest exits and we want to * run its L1 parent, is to reset L1's guest state to the host state specified @@ -11352,7 +11370,6 @@ static void load_vmcs12_host_state(struc struct vmcs12 *vmcs12) { struct kvm_segment seg; - u32 entry_failure_code;

if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER) vcpu->arch.efer = vmcs12->host_ia32_efer; @@ -11379,17 +11396,7 @@ static void load_vmcs12_host_state(struc vcpu->arch.cr4_guest_owned_bits = ~vmcs_readl(CR4_GUEST_HOST_MASK); vmx_set_cr4(vcpu, vmcs12->host_cr4);

- nested_ept_uninit_mmu_context(vcpu); - - /* - * Only PDPTE load can fail as the value of cr3 was checked on entry and - * couldn't have changed. - */ - if (nested_vmx_load_cr3(vcpu, vmcs12->host_cr3, false, &entry_failure_code)) - nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_PDPTE_FAIL); - - if (!enable_ept) - vcpu->arch.walk_mmu->inject_page_fault = kvm_inject_page_fault; + load_vmcs12_mmu_host_state(vcpu, vmcs12);

if (enable_vpid) { /* @@ -11615,6 +11622,9 @@ static void nested_vmx_vmexit(struct kvm * accordingly. */ nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD); + + load_vmcs12_mmu_host_state(vcpu, vmcs12); + /* * The emulated instruction was already skipped in * nested_vmx_run, but the updated RIP was never

Patches currently in stable-queue which might be from wanpeng.li@hotmail.com are

queue-4.14/kvm-x86-don-t-re-execute-instruction-when-not-passing-cr2-value.patch queue-4.14/kvm-x86-ioapic-preserve-read-only-values-in-the-redirection-table.patch queue-4.14/kvm-nvmx-fix-mmu-context-after-vmlaunch-vmresume-failure.patch queue-4.14/kvm-vmx-fix-rflags-cache-during-vcpu-reset.patch queue-4.14/kvm-x86-fix-operand-address-size-during-instruction-decoding.patch queue-4.14/kvm-x86-emulator-return-to-user-mode-on-l1-cpl-0-emulation-failure.patch queue-4.14/kvm-nvmx-nsvm-don-t-intercept-ud-when-running-l2.patch queue-4.14/kvm-x86-fix-softlockup-when-get-the-current-kvmclock.patch queue-4.14/kvm-x86-ioapic-clear-remote-irr-when-entry-is-switched-to-edge-triggered.patch