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Subject[PATCH] x86/hyper-v: define structures from TLFS as packed
Date
Without 'packed' compiler is free to add optimization paddings and re-order
structure fields for randomization/optimization. And structures from
hyperv-tlfs.h are used for hypervisor-guest communication, we need to
ultimately forbid such practices.

Suggested-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
- This is a follow-up to my "[PATCH v2 0/4] x86/kvm/hyper-v: Implement
Direct Mode for synthetic timers" series, as suggested by Thomas I'm
routing it to KVM tree to avoid merge conflicts.
---
arch/x86/include/asm/hyperv-tlfs.h | 50 +++++++++++++++---------------
1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index ebfed56976d2..6a60fa17f6f2 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -271,7 +271,7 @@ union hv_x64_msr_hypercall_contents {
u64 enable:1;
u64 reserved:11;
u64 guest_physical_address:52;
- };
+ } __packed;
};

/*
@@ -283,7 +283,7 @@ struct ms_hyperv_tsc_page {
volatile u64 tsc_scale;
volatile s64 tsc_offset;
u64 reserved2[509];
-};
+} __packed;

/*
* The guest OS needs to register the guest ID with the hypervisor.
@@ -324,7 +324,7 @@ struct hv_reenlightenment_control {
__u64 enabled:1;
__u64 reserved2:15;
__u64 target_vp:32;
-};
+} __packed;

#define HV_X64_MSR_TSC_EMULATION_CONTROL 0x40000107
#define HV_X64_MSR_TSC_EMULATION_STATUS 0x40000108
@@ -332,12 +332,12 @@ struct hv_reenlightenment_control {
struct hv_tsc_emulation_control {
__u64 enabled:1;
__u64 reserved:63;
-};
+} __packed;

struct hv_tsc_emulation_status {
__u64 inprogress:1;
__u64 reserved:63;
-};
+} __packed;

#define HV_X64_MSR_HYPERCALL_ENABLE 0x00000001
#define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT 12
@@ -409,7 +409,7 @@ typedef struct _HV_REFERENCE_TSC_PAGE {
__u32 res1;
__u64 tsc_scale;
__s64 tsc_offset;
-} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
+} __packed HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;

/* Define the number of synthetic interrupt sources. */
#define HV_SYNIC_SINT_COUNT (16)
@@ -466,7 +466,7 @@ union hv_message_flags {
struct {
__u8 msg_pending:1;
__u8 reserved:7;
- };
+ } __packed;
};

/* Define port identifier type. */
@@ -488,7 +488,7 @@ struct hv_message_header {
__u64 sender;
union hv_port_id port;
};
-};
+} __packed;

/* Define synthetic interrupt controller message format. */
struct hv_message {
@@ -496,12 +496,12 @@ struct hv_message {
union {
__u64 payload[HV_MESSAGE_PAYLOAD_QWORD_COUNT];
} u;
-};
+} __packed;

/* Define the synthetic interrupt message page layout. */
struct hv_message_page {
struct hv_message sint_message[HV_SYNIC_SINT_COUNT];
-};
+} __packed;

/* Define timer message payload structure. */
struct hv_timer_message_payload {
@@ -509,7 +509,7 @@ struct hv_timer_message_payload {
__u32 reserved;
__u64 expiration_time; /* When the timer expired */
__u64 delivery_time; /* When the message was delivered */
-};
+} __packed;

/* Define virtual processor assist page structure. */
struct hv_vp_assist_page {
@@ -519,7 +519,7 @@ struct hv_vp_assist_page {
__u64 nested_enlightenments_control[2];
__u32 enlighten_vmentry;
__u64 current_nested_vmcs;
-};
+} __packed;

struct hv_enlightened_vmcs {
u32 revision_id;
@@ -693,7 +693,7 @@ struct hv_enlightened_vmcs {
u32 nested_flush_hypercall:1;
u32 msr_bitmap:1;
u32 reserved:30;
- } hv_enlightenments_control;
+ } __packed hv_enlightenments_control;
u32 hv_vp_id;

u64 hv_vm_id;
@@ -703,7 +703,7 @@ struct hv_enlightened_vmcs {
u64 padding64_5[7];
u64 xss_exit_bitmap;
u64 padding64_6[7];
-};
+} __packed;

#define HV_VMX_ENLIGHTENED_CLEAN_FIELD_NONE 0
#define HV_VMX_ENLIGHTENED_CLEAN_FIELD_IO_BITMAP BIT(0)
@@ -744,7 +744,7 @@ union hv_stimer_config {
u64 reserved_z0:3;
u64 sintx:4;
u64 reserved_z1:44;
- };
+ } __packed;
};


@@ -759,7 +759,7 @@ union hv_synic_scontrol {
struct {
u64 enable:1;
u64 reserved:63;
- };
+ } __packed;
};

/* Define synthetic interrupt source. */
@@ -771,7 +771,7 @@ union hv_synic_sint {
u64 masked:1;
u64 auto_eoi:1;
u64 reserved2:46;
- };
+ } __packed;
};

/* Define the format of the SIMP register */
@@ -781,7 +781,7 @@ union hv_synic_simp {
u64 simp_enabled:1;
u64 preserved:11;
u64 base_simp_gpa:52;
- };
+ } __packed;
};

/* Define the format of the SIEFP register */
@@ -791,34 +791,34 @@ union hv_synic_siefp {
u64 siefp_enabled:1;
u64 preserved:11;
u64 base_siefp_gpa:52;
- };
+ } __packed;
};

struct hv_vpset {
u64 format;
u64 valid_bank_mask;
u64 bank_contents[];
-};
+} __packed;

/* HvCallSendSyntheticClusterIpi hypercall */
struct hv_send_ipi {
u32 vector;
u32 reserved;
u64 cpu_mask;
-};
+} __packed;

/* HvCallSendSyntheticClusterIpiEx hypercall */
struct hv_send_ipi_ex {
u32 vector;
u32 reserved;
struct hv_vpset vp_set;
-};
+} __packed;

/* HvFlushGuestPhysicalAddressSpace hypercalls */
struct hv_guest_mapping_flush {
u64 address_space;
u64 flags;
-};
+} __packed;

/* HvFlushVirtualAddressSpace, HvFlushVirtualAddressList hypercalls */
struct hv_tlb_flush {
@@ -826,7 +826,7 @@ struct hv_tlb_flush {
u64 flags;
u64 processor_mask;
u64 gva_list[];
-};
+} __packed;

/* HvFlushVirtualAddressSpaceEx, HvFlushVirtualAddressListEx hypercalls */
struct hv_tlb_flush_ex {
@@ -834,6 +834,6 @@ struct hv_tlb_flush_ex {
u64 flags;
struct hv_vpset hv_vp_set;
u64 gva_list[];
-};
+} __packed;

#endif
--
2.19.2
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