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Subject[PATCH 4.14 031/165] KVM: vmx: use local variable for current_vmptr when emulating VMPTRST
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sean Christopherson <sean.j.christopherson@intel.com>

[ Upstream commit 0a06d4256674c4e041945b52044941995fee237d ]

Do not expose the address of vmx->nested.current_vmptr to
kvm_write_guest_virt_system() as the resulting __copy_to_user()
call will trigger a WARN when CONFIG_HARDENED_USERCOPY is
enabled.

Opportunistically clean up variable names in handle_vmptrst()
to improve readability, e.g. vmcs_gva is misleading as the
memory operand of VMPTRST is plain memory, not a VMCS.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Tested-by: Peter Shier <pshier@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/vmx.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8108,21 +8108,20 @@ static int handle_vmptrld(struct kvm_vcp
/* Emulate the VMPTRST instruction */
static int handle_vmptrst(struct kvm_vcpu *vcpu)
{
- unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
- u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
- gva_t vmcs_gva;
+ unsigned long exit_qual = vmcs_readl(EXIT_QUALIFICATION);
+ u32 instr_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+ gpa_t current_vmptr = to_vmx(vcpu)->nested.current_vmptr;
struct x86_exception e;
+ gva_t gva;

if (!nested_vmx_check_permission(vcpu))
return 1;

- if (get_vmx_mem_address(vcpu, exit_qualification,
- vmx_instruction_info, true, &vmcs_gva))
+ if (get_vmx_mem_address(vcpu, exit_qual, instr_info, true, &gva))
return 1;
/* *_system ok, nested_vmx_check_permission has verified cpl=0 */
- if (kvm_write_guest_virt_system(vcpu, vmcs_gva,
- (void *)&to_vmx(vcpu)->nested.current_vmptr,
- sizeof(u64), &e)) {
+ if (kvm_write_guest_virt_system(vcpu, gva, (void *)&current_vmptr,
+ sizeof(gpa_t), &e)) {
kvm_inject_page_fault(vcpu, &e);
return 1;
}

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