[PATCH 3/3] kvm: vmx: Reduce size of vmcs_field_to_offset_table

[Jim Mattson <jmattson@google.com>]

The vmcs_field_to_offset_table was a rather sparse table of short
integers with a maximum index of 0x6c16, amounting to 55342 bytes. Now
that we are considering support for multiple VMCS12 formats, it would
be unfortunate to replicate that large, sparse table. Using a
three-dimensional table indexed by VMCS field index, VMCS field type,
and VMCS field width, it's relatively easy to reduce that table to 768
bytes.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx.c | 145 ++++++++++++++++++++++++++++++++---------------------
 1 file changed, 88 insertions(+), 57 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1847000fbb0c..bd601b0984d1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -714,11 +714,15 @@ static struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
 	return &(to_vmx(vcpu)->pi_desc);
 }
 
-#define VMCS12_OFFSET(x) offsetof(struct vmcs12, x)
-#define FIELD(number, name)	[number] = VMCS12_OFFSET(name)
-#define FIELD64(number, name)	[number] = VMCS12_OFFSET(name), \
-				[number##_HIGH] = VMCS12_OFFSET(name)+4
+#define VMCS_FIELD_HIGH(field)  ((field) & 1)
+#define VMCS_FIELD_INDEX(field) (((field) >> 1) & 0x1ff)
+#define VMCS_FIELD_TYPE(field)  (((field) >> 10) & 3)
+#define VMCS_FIELD_WIDTH(field) (((field) >> 13) & 3)
 
+#define VMCS12_OFFSET(x) offsetof(struct vmcs12, x)
+#define FIELD(n, name) \
+	[VMCS_FIELD_INDEX(n)][VMCS_FIELD_TYPE(n)][VMCS_FIELD_WIDTH(n)] = \
+		VMCS12_OFFSET(name)
 
 static unsigned long shadow_read_only_fields[] = {
 	/*
@@ -779,7 +783,7 @@ static unsigned long shadow_read_write_fields[] = {
 static int max_shadow_read_write_fields =
 	ARRAY_SIZE(shadow_read_write_fields);
 
-static const unsigned short vmcs_field_to_offset_table[] = {
+static const unsigned short vmcs_field_to_offset_table[][4][4] = {
 	FIELD(VIRTUAL_PROCESSOR_ID, virtual_processor_id),
 	FIELD(POSTED_INTR_NV, posted_intr_nv),
 	FIELD(GUEST_ES_SELECTOR, guest_es_selector),
@@ -799,39 +803,39 @@ static const unsigned short vmcs_field_to_offset_table[] = {
 	FIELD(HOST_FS_SELECTOR, host_fs_selector),
 	FIELD(HOST_GS_SELECTOR, host_gs_selector),
 	FIELD(HOST_TR_SELECTOR, host_tr_selector),
-	FIELD64(IO_BITMAP_A, io_bitmap_a),
-	FIELD64(IO_BITMAP_B, io_bitmap_b),
-	FIELD64(MSR_BITMAP, msr_bitmap),
-	FIELD64(VM_EXIT_MSR_STORE_ADDR, vm_exit_msr_store_addr),
-	FIELD64(VM_EXIT_MSR_LOAD_ADDR, vm_exit_msr_load_addr),
-	FIELD64(VM_ENTRY_MSR_LOAD_ADDR, vm_entry_msr_load_addr),
-	FIELD64(TSC_OFFSET, tsc_offset),
-	FIELD64(VIRTUAL_APIC_PAGE_ADDR, virtual_apic_page_addr),
-	FIELD64(APIC_ACCESS_ADDR, apic_access_addr),
-	FIELD64(POSTED_INTR_DESC_ADDR, posted_intr_desc_addr),
-	FIELD64(VM_FUNCTION_CONTROL, vm_function_control),
-	FIELD64(EPT_POINTER, ept_pointer),
-	FIELD64(EOI_EXIT_BITMAP0, eoi_exit_bitmap0),
-	FIELD64(EOI_EXIT_BITMAP1, eoi_exit_bitmap1),
-	FIELD64(EOI_EXIT_BITMAP2, eoi_exit_bitmap2),
-	FIELD64(EOI_EXIT_BITMAP3, eoi_exit_bitmap3),
-	FIELD64(EPTP_LIST_ADDRESS, eptp_list_address),
-	FIELD64(XSS_EXIT_BITMAP, xss_exit_bitmap),
-	FIELD64(GUEST_PHYSICAL_ADDRESS, guest_physical_address),
-	FIELD64(VMCS_LINK_POINTER, vmcs_link_pointer),
-	FIELD64(PML_ADDRESS, pml_address),
-	FIELD64(GUEST_IA32_DEBUGCTL, guest_ia32_debugctl),
-	FIELD64(GUEST_IA32_PAT, guest_ia32_pat),
-	FIELD64(GUEST_IA32_EFER, guest_ia32_efer),
-	FIELD64(GUEST_IA32_PERF_GLOBAL_CTRL, guest_ia32_perf_global_ctrl),
-	FIELD64(GUEST_PDPTR0, guest_pdptr0),
-	FIELD64(GUEST_PDPTR1, guest_pdptr1),
-	FIELD64(GUEST_PDPTR2, guest_pdptr2),
-	FIELD64(GUEST_PDPTR3, guest_pdptr3),
-	FIELD64(GUEST_BNDCFGS, guest_bndcfgs),
-	FIELD64(HOST_IA32_PAT, host_ia32_pat),
-	FIELD64(HOST_IA32_EFER, host_ia32_efer),
-	FIELD64(HOST_IA32_PERF_GLOBAL_CTRL, host_ia32_perf_global_ctrl),
+	FIELD(IO_BITMAP_A, io_bitmap_a),
+	FIELD(IO_BITMAP_B, io_bitmap_b),
+	FIELD(MSR_BITMAP, msr_bitmap),
+	FIELD(VM_EXIT_MSR_STORE_ADDR, vm_exit_msr_store_addr),
+	FIELD(VM_EXIT_MSR_LOAD_ADDR, vm_exit_msr_load_addr),
+	FIELD(VM_ENTRY_MSR_LOAD_ADDR, vm_entry_msr_load_addr),
+	FIELD(TSC_OFFSET, tsc_offset),
+	FIELD(VIRTUAL_APIC_PAGE_ADDR, virtual_apic_page_addr),
+	FIELD(APIC_ACCESS_ADDR, apic_access_addr),
+	FIELD(POSTED_INTR_DESC_ADDR, posted_intr_desc_addr),
+	FIELD(VM_FUNCTION_CONTROL, vm_function_control),
+	FIELD(EPT_POINTER, ept_pointer),
+	FIELD(EOI_EXIT_BITMAP0, eoi_exit_bitmap0),
+	FIELD(EOI_EXIT_BITMAP1, eoi_exit_bitmap1),
+	FIELD(EOI_EXIT_BITMAP2, eoi_exit_bitmap2),
+	FIELD(EOI_EXIT_BITMAP3, eoi_exit_bitmap3),
+	FIELD(EPTP_LIST_ADDRESS, eptp_list_address),
+	FIELD(XSS_EXIT_BITMAP, xss_exit_bitmap),
+	FIELD(GUEST_PHYSICAL_ADDRESS, guest_physical_address),
+	FIELD(VMCS_LINK_POINTER, vmcs_link_pointer),
+	FIELD(PML_ADDRESS, pml_address),
+	FIELD(GUEST_IA32_DEBUGCTL, guest_ia32_debugctl),
+	FIELD(GUEST_IA32_PAT, guest_ia32_pat),
+	FIELD(GUEST_IA32_EFER, guest_ia32_efer),
+	FIELD(GUEST_IA32_PERF_GLOBAL_CTRL, guest_ia32_perf_global_ctrl),
+	FIELD(GUEST_PDPTR0, guest_pdptr0),
+	FIELD(GUEST_PDPTR1, guest_pdptr1),
+	FIELD(GUEST_PDPTR2, guest_pdptr2),
+	FIELD(GUEST_PDPTR3, guest_pdptr3),
+	FIELD(GUEST_BNDCFGS, guest_bndcfgs),
+	FIELD(HOST_IA32_PAT, host_ia32_pat),
+	FIELD(HOST_IA32_EFER, host_ia32_efer),
+	FIELD(HOST_IA32_PERF_GLOBAL_CTRL, host_ia32_perf_global_ctrl),
 	FIELD(PIN_BASED_VM_EXEC_CONTROL, pin_based_vm_exec_control),
 	FIELD(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control),
 	FIELD(EXCEPTION_BITMAP, exception_bitmap),
@@ -923,15 +927,56 @@ static const unsigned short vmcs_field_to_offset_table[] = {
 	FIELD(HOST_RIP, host_rip),
 };
 
+enum vmcs_field_width {
+	VMCS_FIELD_WIDTH_U16 = 0,
+	VMCS_FIELD_WIDTH_U64 = 1,
+	VMCS_FIELD_WIDTH_U32 = 2,
+	VMCS_FIELD_WIDTH_NATURAL_WIDTH = 3
+};
+
+static inline int vmcs_field_width(unsigned long field)
+{
+	if (VMCS_FIELD_HIGH(field))	/* the *_HIGH fields are all 32 bit */
+		return VMCS_FIELD_WIDTH_U32;
+	return VMCS_FIELD_WIDTH(field);
+}
+
+enum vmcs_field_type {
+	VMCS_FIELD_TYPE_CONTROL = 0,
+	VMCS_FIELD_TYPE_INFO = 1,
+	VMCS_FIELD_TYPE_GUEST = 2,
+	VMCS_FIELD_TYPE_HOST = 3
+};
+
+static inline int vmcs_field_type(unsigned long field)
+{
+	return VMCS_FIELD_TYPE(field);
+}
+
 static inline short vmcs_field_to_offset(unsigned long field)
 {
-	BUILD_BUG_ON(ARRAY_SIZE(vmcs_field_to_offset_table) > SHRT_MAX);
+	unsigned index = VMCS_FIELD_INDEX(field);
+	unsigned type = VMCS_FIELD_TYPE(field);
+	unsigned width = VMCS_FIELD_WIDTH(field);
+	short offset;
 
-	if (field >= ARRAY_SIZE(vmcs_field_to_offset_table) ||
-	    vmcs_field_to_offset_table[field] == 0)
+	BUILD_BUG_ON(ARRAY_SIZE(vmcs_field_to_offset_table) >
+		     VMCS12_MAX_FIELD_INDEX + 1);
+	if (VMCS_FIELD_HIGH(field) && width != VMCS_FIELD_WIDTH_U64)
 		return -ENOENT;
 
-	return vmcs_field_to_offset_table[field];
+	if (index >= ARRAY_SIZE(vmcs_field_to_offset_table))
+		return -ENOENT;
+
+	offset = vmcs_field_to_offset_table[index][type][width];
+
+	if (offset == 0)
+		return -ENOENT;
+
+	if (VMCS_FIELD_HIGH(field))
+		offset += sizeof(u32);
+
+	return offset;
 }
 
 static inline struct vmcs12 *get_vmcs12(struct kvm_vcpu *vcpu)
@@ -4050,23 +4095,9 @@ static void free_kvm_area(void)
 	}
 }
 
-enum vmcs_field_width {
-	VMCS_FIELD_WIDTH_U16 = 0,
-	VMCS_FIELD_WIDTH_U64 = 1,
-	VMCS_FIELD_WIDTH_U32 = 2,
-	VMCS_FIELD_WIDTH_NATURAL_WIDTH = 3
-};
-
-static inline int vmcs_field_width(unsigned long field)
-{
-	if (0x1 & field)	/* the *_HIGH fields are all 32 bit */
-		return VMCS_FIELD_WIDTH_U32;
-	return (field >> 13) & 0x3 ;
-}
-
 static inline int vmcs_field_readonly(unsigned long field)
 {
-	return (((field >> 10) & 0x3) == 1);
+	return VMCS_FIELD_TYPE(field) == VMCS_FIELD_TYPE_INFO;
 }
 
 static void init_vmcs_shadow_fields(void)
-- 
2.15.1.620.gb9897f4670-goog