linux-kernel - [PATCH 5/5] KVM: x86/xen: Explicitly pad struct compat_vcpu

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Date:   Wed, 10 Feb 2021 10:26:09 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, David Woodhouse <dwmw@...zon.co.uk>
Subject: [PATCH 5/5] KVM: x86/xen: Explicitly pad struct compat_vcpu_info to
 64 bytes

Add a 2 byte pad to struct compat_vcpu_info so that the sum size of its
fields is actually 64 bytes.  The effective size without the padding is
also 64 bytes due to the compiler aligning evtchn_pending_sel to a 4-byte
boundary, but depending on compiler alignment is subtle and unnecessary.

Opportunistically replace spaces with tables in the other fields.

Cc: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/xen.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index 4b32489c0cec..b66a921776f4 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -49,11 +49,12 @@ struct compat_arch_vcpu_info {
 };
 
 struct compat_vcpu_info {
-        uint8_t evtchn_upcall_pending;
-        uint8_t evtchn_upcall_mask;
-        uint32_t evtchn_pending_sel;
-        struct compat_arch_vcpu_info arch;
-        struct pvclock_vcpu_time_info time;
+	uint8_t evtchn_upcall_pending;
+	uint8_t evtchn_upcall_mask;
+	uint16_t pad;
+	uint32_t evtchn_pending_sel;
+	struct compat_arch_vcpu_info arch;
+	struct pvclock_vcpu_time_info time;
 }; /* 64 bytes (x86) */
 
 struct compat_arch_shared_info {
-- 
2.30.0.478.g8a0d178c01-goog