mirror of https://gitee.com/openkylin/linux.git
KVM: VMX: Cache vmcs segment fields
Since the emulator now checks segment limits and access rights, it generates a lot more accesses to the vmcs segment fields. Undo some of the performance hit by cacheing those fields in a read-only cache (the entire cache is invalidated on any write, or on guest exit). Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity
parent
1aa366163b
commit
2fb92db1ec
|
|
@ -136,6 +136,7 @@ enum kvm_reg_ex {
|
|||
VCPU_EXREG_CR3,
|
||||
VCPU_EXREG_RFLAGS,
|
||||
VCPU_EXREG_CPL,
|
||||
VCPU_EXREG_SEGMENTS,
|
||||
};
|
||||
|
||||
enum {
|
||||
|
|
|
|||
|
|
@ -162,6 +162,10 @@ struct vcpu_vmx {
|
|||
u32 ar;
|
||||
} tr, es, ds, fs, gs;
|
||||
} rmode;
|
||||
struct {
|
||||
u32 bitmask; /* 4 bits per segment (1 bit per field) */
|
||||
struct kvm_save_segment seg[8];
|
||||
} segment_cache;
|
||||
int vpid;
|
||||
bool emulation_required;
|
||||
|
||||
|
|
@ -174,6 +178,15 @@ struct vcpu_vmx {
|
|||
bool rdtscp_enabled;
|
||||
};
|
||||
|
||||
enum segment_cache_field {
|
||||
SEG_FIELD_SEL = 0,
|
||||
SEG_FIELD_BASE = 1,
|
||||
SEG_FIELD_LIMIT = 2,
|
||||
SEG_FIELD_AR = 3,
|
||||
|
||||
SEG_FIELD_NR = 4
|
||||
};
|
||||
|
||||
static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
|
||||
{
|
||||
return container_of(vcpu, struct vcpu_vmx, vcpu);
|
||||
|
|
@ -646,6 +659,62 @@ static void vmcs_set_bits(unsigned long field, u32 mask)
|
|||
vmcs_writel(field, vmcs_readl(field) | mask);
|
||||
}
|
||||
|
||||
static void vmx_segment_cache_clear(struct vcpu_vmx *vmx)
|
||||
{
|
||||
vmx->segment_cache.bitmask = 0;
|
||||
}
|
||||
|
||||
static bool vmx_segment_cache_test_set(struct vcpu_vmx *vmx, unsigned seg,
|
||||
unsigned field)
|
||||
{
|
||||
bool ret;
|
||||
u32 mask = 1 << (seg * SEG_FIELD_NR + field);
|
||||
|
||||
if (!(vmx->vcpu.arch.regs_avail & (1 << VCPU_EXREG_SEGMENTS))) {
|
||||
vmx->vcpu.arch.regs_avail |= (1 << VCPU_EXREG_SEGMENTS);
|
||||
vmx->segment_cache.bitmask = 0;
|
||||
}
|
||||
ret = vmx->segment_cache.bitmask & mask;
|
||||
vmx->segment_cache.bitmask |= mask;
|
||||
return ret;
|
||||
}
|
||||
|
||||
static u16 vmx_read_guest_seg_selector(struct vcpu_vmx *vmx, unsigned seg)
|
||||
{
|
||||
u16 *p = &vmx->segment_cache.seg[seg].selector;
|
||||
|
||||
if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_SEL))
|
||||
*p = vmcs_read16(kvm_vmx_segment_fields[seg].selector);
|
||||
return *p;
|
||||
}
|
||||
|
||||
static ulong vmx_read_guest_seg_base(struct vcpu_vmx *vmx, unsigned seg)
|
||||
{
|
||||
ulong *p = &vmx->segment_cache.seg[seg].base;
|
||||
|
||||
if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_BASE))
|
||||
*p = vmcs_readl(kvm_vmx_segment_fields[seg].base);
|
||||
return *p;
|
||||
}
|
||||
|
||||
static u32 vmx_read_guest_seg_limit(struct vcpu_vmx *vmx, unsigned seg)
|
||||
{
|
||||
u32 *p = &vmx->segment_cache.seg[seg].limit;
|
||||
|
||||
if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_LIMIT))
|
||||
*p = vmcs_read32(kvm_vmx_segment_fields[seg].limit);
|
||||
return *p;
|
||||
}
|
||||
|
||||
static u32 vmx_read_guest_seg_ar(struct vcpu_vmx *vmx, unsigned seg)
|
||||
{
|
||||
u32 *p = &vmx->segment_cache.seg[seg].ar;
|
||||
|
||||
if (!vmx_segment_cache_test_set(vmx, seg, SEG_FIELD_AR))
|
||||
*p = vmcs_read32(kvm_vmx_segment_fields[seg].ar_bytes);
|
||||
return *p;
|
||||
}
|
||||
|
||||
static void update_exception_bitmap(struct kvm_vcpu *vcpu)
|
||||
{
|
||||
u32 eb;
|
||||
|
|
@ -1271,9 +1340,11 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
|
|||
break;
|
||||
#ifdef CONFIG_X86_64
|
||||
case MSR_FS_BASE:
|
||||
vmx_segment_cache_clear(vmx);
|
||||
vmcs_writel(GUEST_FS_BASE, data);
|
||||
break;
|
||||
case MSR_GS_BASE:
|
||||
vmx_segment_cache_clear(vmx);
|
||||
vmcs_writel(GUEST_GS_BASE, data);
|
||||
break;
|
||||
case MSR_KERNEL_GS_BASE:
|
||||
|
|
@ -1717,6 +1788,8 @@ static void enter_pmode(struct kvm_vcpu *vcpu)
|
|||
vmx->emulation_required = 1;
|
||||
vmx->rmode.vm86_active = 0;
|
||||
|
||||
vmx_segment_cache_clear(vmx);
|
||||
|
||||
vmcs_write16(GUEST_TR_SELECTOR, vmx->rmode.tr.selector);
|
||||
vmcs_writel(GUEST_TR_BASE, vmx->rmode.tr.base);
|
||||
vmcs_write32(GUEST_TR_LIMIT, vmx->rmode.tr.limit);
|
||||
|
|
@ -1740,6 +1813,8 @@ static void enter_pmode(struct kvm_vcpu *vcpu)
|
|||
fix_pmode_dataseg(VCPU_SREG_GS, &vmx->rmode.gs);
|
||||
fix_pmode_dataseg(VCPU_SREG_FS, &vmx->rmode.fs);
|
||||
|
||||
vmx_segment_cache_clear(vmx);
|
||||
|
||||
vmcs_write16(GUEST_SS_SELECTOR, 0);
|
||||
vmcs_write32(GUEST_SS_AR_BYTES, 0x93);
|
||||
|
||||
|
|
@ -1803,6 +1878,8 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
|
|||
vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
|
||||
}
|
||||
|
||||
vmx_segment_cache_clear(vmx);
|
||||
|
||||
vmx->rmode.tr.selector = vmcs_read16(GUEST_TR_SELECTOR);
|
||||
vmx->rmode.tr.base = vmcs_readl(GUEST_TR_BASE);
|
||||
vmcs_writel(GUEST_TR_BASE, rmode_tss_base(vcpu->kvm));
|
||||
|
|
@ -1879,6 +1956,8 @@ static void enter_lmode(struct kvm_vcpu *vcpu)
|
|||
{
|
||||
u32 guest_tr_ar;
|
||||
|
||||
vmx_segment_cache_clear(to_vmx(vcpu));
|
||||
|
||||
guest_tr_ar = vmcs_read32(GUEST_TR_AR_BYTES);
|
||||
if ((guest_tr_ar & AR_TYPE_MASK) != AR_TYPE_BUSY_64_TSS) {
|
||||
printk(KERN_DEBUG "%s: tss fixup for long mode. \n",
|
||||
|
|
@ -2082,7 +2161,6 @@ static void vmx_get_segment(struct kvm_vcpu *vcpu,
|
|||
struct kvm_segment *var, int seg)
|
||||
{
|
||||
struct vcpu_vmx *vmx = to_vmx(vcpu);
|
||||
struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
|
||||
struct kvm_save_segment *save;
|
||||
u32 ar;
|
||||
|
||||
|
|
@ -2104,13 +2182,13 @@ static void vmx_get_segment(struct kvm_vcpu *vcpu,
|
|||
var->limit = save->limit;
|
||||
ar = save->ar;
|
||||
if (seg == VCPU_SREG_TR
|
||||
|| var->selector == vmcs_read16(sf->selector))
|
||||
|| var->selector == vmx_read_guest_seg_selector(vmx, seg))
|
||||
goto use_saved_rmode_seg;
|
||||
}
|
||||
var->base = vmcs_readl(sf->base);
|
||||
var->limit = vmcs_read32(sf->limit);
|
||||
var->selector = vmcs_read16(sf->selector);
|
||||
ar = vmcs_read32(sf->ar_bytes);
|
||||
var->base = vmx_read_guest_seg_base(vmx, seg);
|
||||
var->limit = vmx_read_guest_seg_limit(vmx, seg);
|
||||
var->selector = vmx_read_guest_seg_selector(vmx, seg);
|
||||
ar = vmx_read_guest_seg_ar(vmx, seg);
|
||||
use_saved_rmode_seg:
|
||||
if ((ar & AR_UNUSABLE_MASK) && !emulate_invalid_guest_state)
|
||||
ar = 0;
|
||||
|
|
@ -2127,14 +2205,13 @@ static void vmx_get_segment(struct kvm_vcpu *vcpu,
|
|||
|
||||
static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)
|
||||
{
|
||||
struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
|
||||
struct kvm_segment s;
|
||||
|
||||
if (to_vmx(vcpu)->rmode.vm86_active) {
|
||||
vmx_get_segment(vcpu, &s, seg);
|
||||
return s.base;
|
||||
}
|
||||
return vmcs_readl(sf->base);
|
||||
return vmx_read_guest_seg_base(to_vmx(vcpu), seg);
|
||||
}
|
||||
|
||||
static int __vmx_get_cpl(struct kvm_vcpu *vcpu)
|
||||
|
|
@ -2146,7 +2223,7 @@ static int __vmx_get_cpl(struct kvm_vcpu *vcpu)
|
|||
&& (kvm_get_rflags(vcpu) & X86_EFLAGS_VM)) /* if virtual 8086 */
|
||||
return 3;
|
||||
|
||||
return vmcs_read16(GUEST_CS_SELECTOR) & 3;
|
||||
return vmx_read_guest_seg_selector(to_vmx(vcpu), VCPU_SREG_CS) & 3;
|
||||
}
|
||||
|
||||
static int vmx_get_cpl(struct kvm_vcpu *vcpu)
|
||||
|
|
@ -2188,6 +2265,8 @@ static void vmx_set_segment(struct kvm_vcpu *vcpu,
|
|||
struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
|
||||
u32 ar;
|
||||
|
||||
vmx_segment_cache_clear(vmx);
|
||||
|
||||
if (vmx->rmode.vm86_active && seg == VCPU_SREG_TR) {
|
||||
vmcs_write16(sf->selector, var->selector);
|
||||
vmx->rmode.tr.selector = var->selector;
|
||||
|
|
@ -2229,7 +2308,7 @@ static void vmx_set_segment(struct kvm_vcpu *vcpu,
|
|||
|
||||
static void vmx_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)
|
||||
{
|
||||
u32 ar = vmcs_read32(GUEST_CS_AR_BYTES);
|
||||
u32 ar = vmx_read_guest_seg_ar(to_vmx(vcpu), VCPU_SREG_CS);
|
||||
|
||||
*db = (ar >> 14) & 1;
|
||||
*l = (ar >> 13) & 1;
|
||||
|
|
@ -2816,6 +2895,8 @@ static int vmx_vcpu_reset(struct kvm_vcpu *vcpu)
|
|||
if (ret != 0)
|
||||
goto out;
|
||||
|
||||
vmx_segment_cache_clear(vmx);
|
||||
|
||||
seg_setup(VCPU_SREG_CS);
|
||||
/*
|
||||
* GUEST_CS_BASE should really be 0xffff0000, but VT vm86 mode
|
||||
|
|
@ -4188,6 +4269,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
|
|||
| (1 << VCPU_EXREG_RFLAGS)
|
||||
| (1 << VCPU_EXREG_CPL)
|
||||
| (1 << VCPU_EXREG_PDPTR)
|
||||
| (1 << VCPU_EXREG_SEGMENTS)
|
||||
| (1 << VCPU_EXREG_CR3));
|
||||
vcpu->arch.regs_dirty = 0;
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue