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authorSean Christopherson <seanjc@google.com>2021-06-10 02:42:22 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2021-06-17 20:09:51 +0300
commit0e75225dfa4c5d5d51291f54a3d2d5895bad38da (patch)
treea39b132021913d2252297e5512ed2f3479aa393b /arch
parent07ffaf343e34b555c9e7ea39a9c81c439a706f13 (diff)
downloadlinux-0e75225dfa4c5d5d51291f54a3d2d5895bad38da.tar.xz
KVM: nVMX: Ensure 64-bit shift when checking VMFUNC bitmap
Use BIT_ULL() instead of an open-coded shift to check whether or not a function is enabled in L1's VMFUNC bitmap. This is a benign bug as KVM supports only bit 0, and will fail VM-Enter if any other bits are set, i.e. bits 63:32 are guaranteed to be zero. Note, "function" is bounded by hardware as VMFUNC will #UD before taking a VM-Exit if the function is greater than 63. Before: if ((vmcs12->vm_function_control & (1 << function)) == 0) 0x000000000001a916 <+118>: mov $0x1,%eax 0x000000000001a91b <+123>: shl %cl,%eax 0x000000000001a91d <+125>: cltq 0x000000000001a91f <+127>: and 0x128(%rbx),%rax After: if (!(vmcs12->vm_function_control & BIT_ULL(function & 63))) 0x000000000001a955 <+117>: mov 0x128(%rbx),%rdx 0x000000000001a95c <+124>: bt %rax,%rdx Fixes: 27c42a1bb867 ("KVM: nVMX: Enable VMFUNC for the L1 hypervisor") Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210609234235.1244004-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/vmx/nested.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index a9906c8344b8..775df9e2ff88 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5598,7 +5598,7 @@ static int handle_vmfunc(struct kvm_vcpu *vcpu)
}
vmcs12 = get_vmcs12(vcpu);
- if ((vmcs12->vm_function_control & (1 << function)) == 0)
+ if (!(vmcs12->vm_function_control & BIT_ULL(function)))
goto fail;
switch (function) {