linux-kernel - [PATCH 2/4] KVM: nVMX: Properly pad 'struct kvm_vmx_nested_state

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Date:   Mon,  3 May 2021 17:08:52 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] KVM: nVMX: Properly pad 'struct kvm_vmx_nested_state_hdr'

Eliminate the probably unwanted hole in 'struct kvm_vmx_nested_state_hdr':

Pre-patch:
struct kvm_vmx_nested_state_hdr {
        __u64                      vmxon_pa;             /*     0     8 */
        __u64                      vmcs12_pa;            /*     8     8 */
        struct {
                __u16              flags;                /*    16     2 */
        } smm;                                           /*    16     2 */

        /* XXX 2 bytes hole, try to pack */

        __u32                      flags;                /*    20     4 */
        __u64                      preemption_timer_deadline; /*    24     8 */
};

Post-patch:
struct kvm_vmx_nested_state_hdr {
        __u64                      vmxon_pa;             /*     0     8 */
        __u64                      vmcs12_pa;            /*     8     8 */
        struct {
                __u16              flags;                /*    16     2 */
        } smm;                                           /*    16     2 */
        __u16                      pad;                  /*    18     2 */
        __u32                      flags;                /*    20     4 */
        __u64                      preemption_timer_deadline; /*    24     8 */
};

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/include/uapi/asm/kvm.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 5a3022c8af82..0662f644aad9 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -437,6 +437,8 @@ struct kvm_vmx_nested_state_hdr {
 		__u16 flags;
 	} smm;
 
+	__u16 pad;
+
 	__u32 flags;
 	__u64 preemption_timer_deadline;
 };
-- 
2.30.2