[PATCH 09/43] KVM: nVMX: Track vmcs12 offsets for shadowed VMCS fields
From: Paolo Bonzini
Date: Thu Jun 13 2019 - 13:12:59 EST
From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
The vmcs12 fields offsets are constant and known at compile time. Store
the associated offset for each shadowed field to avoid the costly lookup
in vmcs_field_to_offset() when copying between vmcs12 and the shadow
VMCS. Avoiding the costly lookup reduces the latency of copying by
~100 cycles in each direction.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 96 +++++++++++++++++++----------------
arch/x86/kvm/vmx/vmcs12.h | 57 +++++++--------------
arch/x86/kvm/vmx/vmcs_shadow_fields.h | 74 +++++++++++++--------------
3 files changed, 108 insertions(+), 119 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index cd51ef68434e..376fd9eabe42 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -41,15 +41,19 @@ enum {
#define vmx_vmread_bitmap (vmx_bitmap[VMX_VMREAD_BITMAP])
#define vmx_vmwrite_bitmap (vmx_bitmap[VMX_VMWRITE_BITMAP])
-static u16 shadow_read_only_fields[] = {
-#define SHADOW_FIELD_RO(x) x,
+struct shadow_vmcs_field {
+ u16 encoding;
+ u16 offset;
+};
+static struct shadow_vmcs_field shadow_read_only_fields[] = {
+#define SHADOW_FIELD_RO(x, y) { x, offsetof(struct vmcs12, y) },
#include "vmcs_shadow_fields.h"
};
static int max_shadow_read_only_fields =
ARRAY_SIZE(shadow_read_only_fields);
-static u16 shadow_read_write_fields[] = {
-#define SHADOW_FIELD_RW(x) x,
+static struct shadow_vmcs_field shadow_read_write_fields[] = {
+#define SHADOW_FIELD_RW(x, y) { x, offsetof(struct vmcs12, y) },
#include "vmcs_shadow_fields.h"
};
static int max_shadow_read_write_fields =
@@ -63,37 +67,39 @@ static void init_vmcs_shadow_fields(void)
memset(vmx_vmwrite_bitmap, 0xff, PAGE_SIZE);
for (i = j = 0; i < max_shadow_read_only_fields; i++) {
- u16 field = shadow_read_only_fields[i];
+ struct shadow_vmcs_field entry = shadow_read_only_fields[i];
+ u16 field = entry.encoding;
if (vmcs_field_width(field) == VMCS_FIELD_WIDTH_U64 &&
(i + 1 == max_shadow_read_only_fields ||
- shadow_read_only_fields[i + 1] != field + 1))
+ shadow_read_only_fields[i + 1].encoding != field + 1))
pr_err("Missing field from shadow_read_only_field %x\n",
field + 1);
clear_bit(field, vmx_vmread_bitmap);
-#ifdef CONFIG_X86_64
if (field & 1)
+#ifdef CONFIG_X86_64
continue;
+#else
+ entry.offset += sizeof(u32);
#endif
- if (j < i)
- shadow_read_only_fields[j] = field;
- j++;
+ shadow_read_only_fields[j++] = entry;
}
max_shadow_read_only_fields = j;
for (i = j = 0; i < max_shadow_read_write_fields; i++) {
- u16 field = shadow_read_write_fields[i];
+ struct shadow_vmcs_field entry = shadow_read_write_fields[i];
+ u16 field = entry.encoding;
if (vmcs_field_width(field) == VMCS_FIELD_WIDTH_U64 &&
(i + 1 == max_shadow_read_write_fields ||
- shadow_read_write_fields[i + 1] != field + 1))
+ shadow_read_write_fields[i + 1].encoding != field + 1))
pr_err("Missing field from shadow_read_write_field %x\n",
field + 1);
WARN_ONCE(field >= GUEST_ES_AR_BYTES &&
field <= GUEST_TR_AR_BYTES,
- "Update vmcs12_write_any() to expose AR_BYTES RW");
+ "Update vmcs12_write_any() to drop reserved bits from AR_BYTES");
/*
* PML and the preemption timer can be emulated, but the
@@ -119,13 +125,13 @@ static void init_vmcs_shadow_fields(void)
clear_bit(field, vmx_vmwrite_bitmap);
clear_bit(field, vmx_vmread_bitmap);
-#ifdef CONFIG_X86_64
if (field & 1)
+#ifdef CONFIG_X86_64
continue;
+#else
+ entry.offset += sizeof(u32);
#endif
- if (j < i)
- shadow_read_write_fields[j] = field;
- j++;
+ shadow_read_write_fields[j++] = entry;
}
max_shadow_read_write_fields = j;
}
@@ -1308,7 +1314,8 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
{
struct vmcs *shadow_vmcs = vmx->vmcs01.shadow_vmcs;
struct vmcs12 *vmcs12 = get_vmcs12(&vmx->vcpu);
- unsigned long field;
+ struct shadow_vmcs_field field;
+ unsigned long val;
int i;
preempt_disable();
@@ -1317,7 +1324,8 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
for (i = 0; i < max_shadow_read_write_fields; i++) {
field = shadow_read_write_fields[i];
- vmcs12_write_any(vmcs12, field, __vmcs_readl(field));
+ val = __vmcs_readl(field.encoding);
+ vmcs12_write_any(vmcs12, field.encoding, field.offset, val);
}
vmcs_clear(shadow_vmcs);
@@ -1328,7 +1336,7 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
{
- const u16 *fields[] = {
+ const struct shadow_vmcs_field *fields[] = {
shadow_read_write_fields,
shadow_read_only_fields
};
@@ -1336,18 +1344,20 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
max_shadow_read_write_fields,
max_shadow_read_only_fields
};
- int i, q;
- unsigned long field;
- u64 field_value = 0;
struct vmcs *shadow_vmcs = vmx->vmcs01.shadow_vmcs;
+ struct vmcs12 *vmcs12 = get_vmcs12(&vmx->vcpu);
+ struct shadow_vmcs_field field;
+ unsigned long val;
+ int i, q;
vmcs_load(shadow_vmcs);
for (q = 0; q < ARRAY_SIZE(fields); q++) {
for (i = 0; i < max_fields[q]; i++) {
field = fields[q][i];
- vmcs12_read_any(get_vmcs12(&vmx->vcpu), field, &field_value);
- __vmcs_writel(field, field_value);
+ val = vmcs12_read_any(vmcs12, field.encoding,
+ field.offset);
+ __vmcs_writel(field.encoding, val);
}
}
@@ -2144,6 +2154,8 @@ static void prepare_vmcs02_full(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
vmcs_write32(GUEST_TR_LIMIT, vmcs12->guest_tr_limit);
vmcs_write32(GUEST_GDTR_LIMIT, vmcs12->guest_gdtr_limit);
vmcs_write32(GUEST_IDTR_LIMIT, vmcs12->guest_idtr_limit);
+ vmcs_write32(GUEST_CS_AR_BYTES, vmcs12->guest_cs_ar_bytes);
+ vmcs_write32(GUEST_SS_AR_BYTES, vmcs12->guest_ss_ar_bytes);
vmcs_write32(GUEST_ES_AR_BYTES, vmcs12->guest_es_ar_bytes);
vmcs_write32(GUEST_DS_AR_BYTES, vmcs12->guest_ds_ar_bytes);
vmcs_write32(GUEST_FS_AR_BYTES, vmcs12->guest_fs_ar_bytes);
@@ -2240,23 +2252,12 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
u32 *entry_failure_code)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- struct hv_enlightened_vmcs *hv_evmcs = vmx->nested.hv_evmcs;
if (vmx->nested.dirty_vmcs12 || vmx->nested.hv_evmcs) {
prepare_vmcs02_full(vmx, vmcs12);
vmx->nested.dirty_vmcs12 = false;
}
- /*
- * First, the fields that are shadowed. This must be kept in sync
- * with vmcs_shadow_fields.h.
- */
- if (!hv_evmcs || !(hv_evmcs->hv_clean_fields &
- HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP2)) {
- vmcs_write32(GUEST_CS_AR_BYTES, vmcs12->guest_cs_ar_bytes);
- vmcs_write32(GUEST_SS_AR_BYTES, vmcs12->guest_ss_ar_bytes);
- }
-
if (vmx->nested.nested_run_pending &&
(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) {
kvm_set_dr(vcpu, 7, vmcs12->guest_dr7);
@@ -4372,6 +4373,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
int len;
gva_t gva = 0;
struct vmcs12 *vmcs12;
+ short offset;
if (!nested_vmx_check_permission(vcpu))
return 1;
@@ -4393,11 +4395,15 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
/* Decode instruction info and find the field to read */
field = kvm_register_readl(vcpu, (((vmx_instruction_info) >> 28) & 0xf));
- /* Read the field, zero-extended to a u64 field_value */
- if (vmcs12_read_any(vmcs12, field, &field_value) < 0)
+
+ offset = vmcs_field_to_offset(field);
+ if (offset < 0)
return nested_vmx_failValid(vcpu,
VMXERR_UNSUPPORTED_VMCS_COMPONENT);
+ /* Read the field, zero-extended to a u64 field_value */
+ field_value = vmcs12_read_any(vmcs12, field, offset);
+
/*
* Now copy part of this value to register or memory, as requested.
* Note that the number of bits actually copied is 32 or 64 depending
@@ -4437,6 +4443,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
u64 field_value = 0;
struct x86_exception e;
struct vmcs12 *vmcs12;
+ short offset;
if (!nested_vmx_check_permission(vcpu))
return 1;
@@ -4481,6 +4488,11 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
vmcs12 = get_shadow_vmcs12(vcpu);
}
+ offset = vmcs_field_to_offset(field);
+ if (offset < 0)
+ return nested_vmx_failValid(vcpu,
+ VMXERR_UNSUPPORTED_VMCS_COMPONENT);
+
/*
* Some Intel CPUs intentionally drop the reserved bits of the AR byte
* fields on VMWRITE. Emulate this behavior to ensure consistent KVM
@@ -4492,9 +4504,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
if (field >= GUEST_ES_AR_BYTES && field <= GUEST_TR_AR_BYTES)
field_value &= 0x1f0ff;
- if (vmcs12_write_any(vmcs12, field, field_value) < 0)
- return nested_vmx_failValid(vcpu,
- VMXERR_UNSUPPORTED_VMCS_COMPONENT);
+ vmcs12_write_any(vmcs12, field, offset, field_value);
/*
* Do not track vmcs12 dirty-state if in guest-mode
@@ -4502,7 +4512,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
*/
if (!is_guest_mode(vcpu)) {
switch (field) {
-#define SHADOW_FIELD_RW(x) case x:
+#define SHADOW_FIELD_RW(x, y) case x:
#include "vmcs_shadow_fields.h"
/*
* The fields that can be updated by L1 without a vmexit are
@@ -4511,7 +4521,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
*/
break;
-#define SHADOW_FIELD_RO(x) case x:
+#define SHADOW_FIELD_RO(x, y) case x:
#include "vmcs_shadow_fields.h"
/*
* L1 can read these fields without exiting, ensure the
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h
index 3a742428ad17..9cd26099fcc0 100644
--- a/arch/x86/kvm/vmx/vmcs12.h
+++ b/arch/x86/kvm/vmx/vmcs12.h
@@ -394,69 +394,48 @@ static inline short vmcs_field_to_offset(unsigned long field)
#undef ROL16
-/*
- * Read a vmcs12 field. Since these can have varying lengths and we return
- * one type, we chose the biggest type (u64) and zero-extend the return value
- * to that size. Note that the caller, handle_vmread, might need to use only
- * some of the bits we return here (e.g., on 32-bit guests, only 32 bits of
- * 64-bit fields are to be returned).
- */
-static inline int vmcs12_read_any(struct vmcs12 *vmcs12,
- unsigned long field, u64 *ret)
+static inline u64 vmcs12_read_any(struct vmcs12 *vmcs12, unsigned long field,
+ u16 offset)
{
- short offset = vmcs_field_to_offset(field);
- char *p;
-
- if (offset < 0)
- return offset;
-
- p = (char *)vmcs12 + offset;
+ char *p = (char *)vmcs12 + offset;
switch (vmcs_field_width(field)) {
case VMCS_FIELD_WIDTH_NATURAL_WIDTH:
- *ret = *((natural_width *)p);
- return 0;
+ return *((natural_width *)p);
case VMCS_FIELD_WIDTH_U16:
- *ret = *((u16 *)p);
- return 0;
+ return *((u16 *)p);
case VMCS_FIELD_WIDTH_U32:
- *ret = *((u32 *)p);
- return 0;
+ return *((u32 *)p);
case VMCS_FIELD_WIDTH_U64:
- *ret = *((u64 *)p);
- return 0;
+ return *((u64 *)p);
default:
- WARN_ON(1);
- return -ENOENT;
+ WARN_ON_ONCE(1);
+ return -1;
}
}
-static inline int vmcs12_write_any(struct vmcs12 *vmcs12,
- unsigned long field, u64 field_value){
- short offset = vmcs_field_to_offset(field);
+static inline void vmcs12_write_any(struct vmcs12 *vmcs12, unsigned long field,
+ u16 offset, u64 field_value)
+{
char *p = (char *)vmcs12 + offset;
- if (offset < 0)
- return offset;
-
switch (vmcs_field_width(field)) {
case VMCS_FIELD_WIDTH_U16:
*(u16 *)p = field_value;
- return 0;
+ break;
case VMCS_FIELD_WIDTH_U32:
*(u32 *)p = field_value;
- return 0;
+ break;
case VMCS_FIELD_WIDTH_U64:
*(u64 *)p = field_value;
- return 0;
+ break;
case VMCS_FIELD_WIDTH_NATURAL_WIDTH:
*(natural_width *)p = field_value;
- return 0;
+ break;
default:
- WARN_ON(1);
- return -ENOENT;
+ WARN_ON_ONCE(1);
+ break;
}
-
}
#endif /* __KVM_X86_VMX_VMCS12_H */
diff --git a/arch/x86/kvm/vmx/vmcs_shadow_fields.h b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
index 97dd5295be31..2cfa19ca158e 100644
--- a/arch/x86/kvm/vmx/vmcs_shadow_fields.h
+++ b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
@@ -1,8 +1,8 @@
#ifndef SHADOW_FIELD_RO
-#define SHADOW_FIELD_RO(x)
+#define SHADOW_FIELD_RO(x, y)
#endif
#ifndef SHADOW_FIELD_RW
-#define SHADOW_FIELD_RW(x)
+#define SHADOW_FIELD_RW(x, y)
#endif
/*
@@ -28,47 +28,47 @@
*/
/* 16-bits */
-SHADOW_FIELD_RW(GUEST_INTR_STATUS)
-SHADOW_FIELD_RW(GUEST_PML_INDEX)
-SHADOW_FIELD_RW(HOST_FS_SELECTOR)
-SHADOW_FIELD_RW(HOST_GS_SELECTOR)
+SHADOW_FIELD_RW(GUEST_INTR_STATUS, guest_intr_status)
+SHADOW_FIELD_RW(GUEST_PML_INDEX, guest_pml_index)
+SHADOW_FIELD_RW(HOST_FS_SELECTOR, host_fs_selector)
+SHADOW_FIELD_RW(HOST_GS_SELECTOR, host_gs_selector)
/* 32-bits */
-SHADOW_FIELD_RO(VM_EXIT_REASON)
-SHADOW_FIELD_RO(VM_EXIT_INTR_INFO)
-SHADOW_FIELD_RO(VM_EXIT_INSTRUCTION_LEN)
-SHADOW_FIELD_RO(IDT_VECTORING_INFO_FIELD)
-SHADOW_FIELD_RO(IDT_VECTORING_ERROR_CODE)
-SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE)
-SHADOW_FIELD_RO(GUEST_CS_AR_BYTES)
-SHADOW_FIELD_RO(GUEST_SS_AR_BYTES)
-SHADOW_FIELD_RW(CPU_BASED_VM_EXEC_CONTROL)
-SHADOW_FIELD_RW(EXCEPTION_BITMAP)
-SHADOW_FIELD_RW(VM_ENTRY_EXCEPTION_ERROR_CODE)
-SHADOW_FIELD_RW(VM_ENTRY_INTR_INFO_FIELD)
-SHADOW_FIELD_RW(VM_ENTRY_INSTRUCTION_LEN)
-SHADOW_FIELD_RW(TPR_THRESHOLD)
-SHADOW_FIELD_RW(GUEST_INTERRUPTIBILITY_INFO)
-SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE)
+SHADOW_FIELD_RO(VM_EXIT_REASON, vm_exit_reason)
+SHADOW_FIELD_RO(VM_EXIT_INTR_INFO, vm_exit_intr_info)
+SHADOW_FIELD_RO(VM_EXIT_INSTRUCTION_LEN, vm_exit_instruction_len)
+SHADOW_FIELD_RO(IDT_VECTORING_INFO_FIELD, idt_vectoring_info_field)
+SHADOW_FIELD_RO(IDT_VECTORING_ERROR_CODE, idt_vectoring_error_code)
+SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code)
+SHADOW_FIELD_RO(GUEST_CS_AR_BYTES, guest_cs_ar_bytes)
+SHADOW_FIELD_RO(GUEST_SS_AR_BYTES, guest_ss_ar_bytes)
+SHADOW_FIELD_RW(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control)
+SHADOW_FIELD_RW(EXCEPTION_BITMAP, exception_bitmap)
+SHADOW_FIELD_RW(VM_ENTRY_EXCEPTION_ERROR_CODE, vm_entry_exception_error_code)
+SHADOW_FIELD_RW(VM_ENTRY_INTR_INFO_FIELD, vm_entry_intr_info_field)
+SHADOW_FIELD_RW(VM_ENTRY_INSTRUCTION_LEN, vm_entry_instruction_len)
+SHADOW_FIELD_RW(TPR_THRESHOLD, tpr_threshold)
+SHADOW_FIELD_RW(GUEST_INTERRUPTIBILITY_INFO, guest_interruptibility_info)
+SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value)
/* Natural width */
-SHADOW_FIELD_RO(EXIT_QUALIFICATION)
-SHADOW_FIELD_RO(GUEST_LINEAR_ADDRESS)
-SHADOW_FIELD_RW(GUEST_RIP)
-SHADOW_FIELD_RW(GUEST_RSP)
-SHADOW_FIELD_RW(GUEST_CR0)
-SHADOW_FIELD_RW(GUEST_CR3)
-SHADOW_FIELD_RW(GUEST_CR4)
-SHADOW_FIELD_RW(GUEST_RFLAGS)
-SHADOW_FIELD_RW(CR0_GUEST_HOST_MASK)
-SHADOW_FIELD_RW(CR0_READ_SHADOW)
-SHADOW_FIELD_RW(CR4_READ_SHADOW)
-SHADOW_FIELD_RW(HOST_FS_BASE)
-SHADOW_FIELD_RW(HOST_GS_BASE)
+SHADOW_FIELD_RO(EXIT_QUALIFICATION, exit_qualification)
+SHADOW_FIELD_RO(GUEST_LINEAR_ADDRESS, guest_linear_address)
+SHADOW_FIELD_RW(GUEST_RIP, guest_rip)
+SHADOW_FIELD_RW(GUEST_RSP, guest_rsp)
+SHADOW_FIELD_RW(GUEST_CR0, guest_cr0)
+SHADOW_FIELD_RW(GUEST_CR3, guest_cr3)
+SHADOW_FIELD_RW(GUEST_CR4, guest_cr4)
+SHADOW_FIELD_RW(GUEST_RFLAGS, guest_rflags)
+SHADOW_FIELD_RW(CR0_GUEST_HOST_MASK, cr0_guest_host_mask)
+SHADOW_FIELD_RW(CR0_READ_SHADOW, cr0_read_shadow)
+SHADOW_FIELD_RW(CR4_READ_SHADOW, cr4_read_shadow)
+SHADOW_FIELD_RW(HOST_FS_BASE, host_fs_base)
+SHADOW_FIELD_RW(HOST_GS_BASE, host_gs_base)
/* 64-bit */
-SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS)
-SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH)
+SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS, guest_physical_address)
+SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH, guest_physical_address)
#undef SHADOW_FIELD_RO
#undef SHADOW_FIELD_RW
--
1.8.3.1