linux-kernel - [PATCH RFC 15/19] x86/hyperv: Fix 'struct hv_enlightened

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Message-Id: <20220307145023.1913205-16-vkuznets@redhat.com>
Date:   Mon,  7 Mar 2022 15:50:19 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        linux-hyperv@...r.kernel.org,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH RFC 15/19] x86/hyperv: Fix 'struct hv_enlightened_vmcs' definition

Section 1.9 of TLFS v6.0b says:

"All structures are padded in such a way that fields are aligned
naturally (that is, an 8-byte field is aligned to an offset of 8 bytes
and so on)".

'struct enlightened_vmcs' has a glitch:

...
        struct {
                u32                nested_flush_hypercall:1; /*   836: 0  4 */
                u32                msr_bitmap:1;         /*   836: 1  4 */
                u32                reserved:30;          /*   836: 2  4 */
        } hv_enlightenments_control;                     /*   836     4 */
        u32                        hv_vp_id;             /*   840     4 */
        u64                        hv_vm_id;             /*   844     8 */
        u64                        partition_assist_page; /*   852     8 */
...

And the observed values in 'partition_assist_page' make no sense at
all. Fix the layout by padding the structure properly.

Fixes: 68d1eb72ee99 ("x86/hyper-v: define struct hv_enlightened_vmcs and clean field bits")
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/include/asm/hyperv-tlfs.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 5225a85c08c3..e7ddae8e02c6 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -548,7 +548,7 @@ struct hv_enlightened_vmcs {
 	u64 guest_rip;
 
 	u32 hv_clean_fields;
-	u32 hv_padding_32;
+	u32 padding32_1;
 	u32 hv_synthetic_controls;
 	struct {
 		u32 nested_flush_hypercall:1;
@@ -556,7 +556,7 @@ struct hv_enlightened_vmcs {
 		u32 reserved:30;
 	}  __packed hv_enlightenments_control;
 	u32 hv_vp_id;
-
+	u32 padding32_2;
 	u64 hv_vm_id;
 	u64 partition_assist_page;
 	u64 padding64_4[4];
-- 
2.35.1