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    Subject[PATCH 4.19 066/306] KVM: nVMX: reset cache/shadows when switching loaded VMCS
    Date
    From: Sean Christopherson <sean.j.christopherson@intel.com>

    [ Upstream commit b7031fd40fcc741b0f9b0c04c8d844e445858b84 ]

    Reset the vm_{entry,exit}_controls_shadow variables as well as the
    segment cache after loading a new VMCS in vmx_switch_vmcs(). The
    shadows/cache track VMCS data, i.e. they're stale every time we
    switch to a new VMCS regardless of reason.

    This fixes a bug where stale control shadows would be consumed after
    a nested VMExit due to a failed consistency check.

    Suggested-by: Jim Mattson <jmattson@google.com>
    Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    Reviewed-by: Jim Mattson <jmattson@google.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/kvm/vmx.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
    index 1ab4bb3d6a040..fe7fdd666f091 100644
    --- a/arch/x86/kvm/vmx.c
    +++ b/arch/x86/kvm/vmx.c
    @@ -11013,6 +11013,10 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs)
    vmx->loaded_vmcs = vmcs;
    vmx_vcpu_load(vcpu, cpu);
    put_cpu();
    +
    + vm_entry_controls_reset_shadow(vmx);
    + vm_exit_controls_reset_shadow(vmx);
    + vmx_segment_cache_clear(vmx);
    }

    /*
    @@ -12699,7 +12703,6 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
    vmx->nested.vmcs01_guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);

    vmx_switch_vmcs(vcpu, &vmx->nested.vmcs02);
    - vmx_segment_cache_clear(vmx);

    if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)
    vcpu->arch.tsc_offset += vmcs12->tsc_offset;
    @@ -13530,9 +13533,6 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
    }

    vmx_switch_vmcs(vcpu, &vmx->vmcs01);
    - vm_entry_controls_reset_shadow(vmx);
    - vm_exit_controls_reset_shadow(vmx);
    - vmx_segment_cache_clear(vmx);

    /* Update any VMCS fields that might have changed while L2 ran */
    vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);
    --
    2.20.1


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