[PATCH] KVM: Segment access cleanup

From: Avi Kivity
Date: Sun Nov 12 2006 - 09:56:30 EST

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Instead of using pasting macros, put the vmx segment field indices into
an array and use the array to access the fields indirectly. Cleaner code
as well as ~200 bytes saved.

Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>

Index: linux-2.6/drivers/kvm/kvm.h
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm.h
+++ linux-2.6/drivers/kvm/kvm.h
@@ -195,10 +195,10 @@ struct kvm_vcpu {
unsigned char mmio_data[8];
gpa_t mmio_phys_addr;

- struct{
+ struct {
int active;
u8 save_iopl;
- struct {
+ struct kvm_save_segment {
u16 selector;
unsigned long base;
u32 limit;
Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -62,6 +62,41 @@ static struct kvm_stats_debugfs_item {

static struct dentry *debugfs_dir;

+enum {
+ VCPU_SREG_CS,
+ VCPU_SREG_DS,
+ VCPU_SREG_ES,
+ VCPU_SREG_FS,
+ VCPU_SREG_GS,
+ VCPU_SREG_SS,
+ VCPU_SREG_TR,
+ VCPU_SREG_LDTR,
+};
+
+#define VMX_SEGMENT_FIELD(seg) \
+ [VCPU_SREG_##seg] { \
+ GUEST_##seg##_SELECTOR, \
+ GUEST_##seg##_BASE, \
+ GUEST_##seg##_LIMIT, \
+ GUEST_##seg##_AR_BYTES, \
+ }
+
+static struct kvm_vmx_segment_field {
+ unsigned selector;
+ unsigned base;
+ unsigned limit;
+ unsigned ar_bytes;
+} kvm_vmx_segment_fields[] = {
+ VMX_SEGMENT_FIELD(CS),
+ VMX_SEGMENT_FIELD(DS),
+ VMX_SEGMENT_FIELD(ES),
+ VMX_SEGMENT_FIELD(FS),
+ VMX_SEGMENT_FIELD(GS),
+ VMX_SEGMENT_FIELD(SS),
+ VMX_SEGMENT_FIELD(TR),
+ VMX_SEGMENT_FIELD(LDTR),
+};
+
static const u32 vmx_msr_index[] = {
#ifdef __x86_64__
MSR_SYSCALL_MASK, MSR_LSTAR, MSR_CSTAR, MSR_KERNEL_GS_BASE,
@@ -689,6 +724,22 @@ static void update_exception_bitmap(stru
vmcs_write32(EXCEPTION_BITMAP, 1 << PF_VECTOR);
}

+static void fix_pmode_dataseg(int seg, struct kvm_save_segment *save)
+{
+ struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
+
+ if (vmcs_readl(sf->base) == save->base) {
+ vmcs_write16(sf->selector, save->selector);
+ vmcs_writel(sf->base, save->base);
+ vmcs_write32(sf->limit, save->limit);
+ vmcs_write32(sf->ar_bytes, save->ar);
+ } else {
+ u32 dpl = (vmcs_read16(sf->selector) & SELECTOR_RPL_MASK)
+ << AR_DPL_SHIFT;
+ vmcs_write32(sf->ar_bytes, 0x93 | dpl);
+ }
+}
+
static void enter_pmode(struct kvm_vcpu *vcpu)
{
unsigned long flags;
@@ -709,24 +760,10 @@ static void enter_pmode(struct kvm_vcpu

update_exception_bitmap(vcpu);

- #define FIX_PMODE_DATASEG(seg, save) { \
- if (vmcs_readl(GUEST_##seg##_BASE) == save.base) { \
- vmcs_write16(GUEST_##seg##_SELECTOR, save.selector); \
- vmcs_writel(GUEST_##seg##_BASE, save.base); \
- vmcs_write32(GUEST_##seg##_LIMIT, save.limit); \
- vmcs_write32(GUEST_##seg##_AR_BYTES, save.ar); \
- } else { \
- u32 dpl = (vmcs_read16(GUEST_##seg##_SELECTOR) & \
- SELECTOR_RPL_MASK) << AR_DPL_SHIFT; \
- vmcs_write32(GUEST_##seg##_AR_BYTES, 0x93 | dpl); \
- } \
- }
-
- FIX_PMODE_DATASEG(ES, vcpu->rmode.es);
- FIX_PMODE_DATASEG(DS, vcpu->rmode.ds);
- FIX_PMODE_DATASEG(GS, vcpu->rmode.gs);
- FIX_PMODE_DATASEG(FS, vcpu->rmode.fs);
-
+ fix_pmode_dataseg(VCPU_SREG_ES, &vcpu->rmode.es);
+ fix_pmode_dataseg(VCPU_SREG_DS, &vcpu->rmode.ds);
+ fix_pmode_dataseg(VCPU_SREG_GS, &vcpu->rmode.gs);
+ fix_pmode_dataseg(VCPU_SREG_FS, &vcpu->rmode.fs);

vmcs_write16(GUEST_SS_SELECTOR, 0);
vmcs_write32(GUEST_SS_AR_BYTES, 0x93);
@@ -742,6 +779,19 @@ static int rmode_tss_base(struct kvm* kv
return base_gfn << PAGE_SHIFT;
}

+static void fix_rmode_seg(int seg, struct kvm_save_segment *save)
+{
+ struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
+
+ save->selector = vmcs_read16(sf->selector);
+ save->base = vmcs_readl(sf->base);
+ save->limit = vmcs_read32(sf->limit);
+ save->ar = vmcs_read32(sf->ar_bytes);
+ vmcs_write16(sf->selector, vmcs_readl(sf->base) >> 4);
+ vmcs_write32(sf->limit, 0xffff);
+ vmcs_write32(sf->ar_bytes, 0xf3);
+}
+
static void enter_rmode(struct kvm_vcpu *vcpu)
{
unsigned long flags;
@@ -766,17 +816,6 @@ static void enter_rmode(struct kvm_vcpu
vmcs_writel(GUEST_CR4, vmcs_readl(GUEST_CR4) | CR4_VME_MASK);
update_exception_bitmap(vcpu);

- #define FIX_RMODE_SEG(seg, save) { \
- save.selector = vmcs_read16(GUEST_##seg##_SELECTOR); \
- save.base = vmcs_readl(GUEST_##seg##_BASE); \
- save.limit = vmcs_read32(GUEST_##seg##_LIMIT); \
- save.ar = vmcs_read32(GUEST_##seg##_AR_BYTES); \
- vmcs_write16(GUEST_##seg##_SELECTOR, \
- vmcs_readl(GUEST_##seg##_BASE) >> 4); \
- vmcs_write32(GUEST_##seg##_LIMIT, 0xffff); \
- vmcs_write32(GUEST_##seg##_AR_BYTES, 0xf3); \
- }
-
vmcs_write16(GUEST_SS_SELECTOR, vmcs_readl(GUEST_SS_BASE) >> 4);
vmcs_write32(GUEST_SS_LIMIT, 0xffff);
vmcs_write32(GUEST_SS_AR_BYTES, 0xf3);
@@ -784,10 +823,10 @@ static void enter_rmode(struct kvm_vcpu
vmcs_write32(GUEST_CS_AR_BYTES, 0xf3);
vmcs_write16(GUEST_CS_SELECTOR, vmcs_readl(GUEST_CS_BASE) >> 4);

- FIX_RMODE_SEG(ES, vcpu->rmode.es);
- FIX_RMODE_SEG(DS, vcpu->rmode.ds);
- FIX_RMODE_SEG(GS, vcpu->rmode.gs);
- FIX_RMODE_SEG(FS, vcpu->rmode.fs);
+ fix_rmode_seg(VCPU_SREG_ES, &vcpu->rmode.es);
+ fix_rmode_seg(VCPU_SREG_DS, &vcpu->rmode.ds);
+ fix_rmode_seg(VCPU_SREG_GS, &vcpu->rmode.gs);
+ fix_rmode_seg(VCPU_SREG_FS, &vcpu->rmode.fs);
}

static int init_rmode_tss(struct kvm* kvm)
@@ -1116,6 +1155,16 @@ static void vmcs_write32_fixedbits(u32 m
vmcs_write32(vmcs_field, val);
}

+static void seg_setup(int seg)
+{
+ struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
+
+ vmcs_write16(sf->selector, 0);
+ vmcs_writel(sf->base, 0);
+ vmcs_write32(sf->limit, 0xffff);
+ vmcs_write32(sf->ar_bytes, 0x93);
+}
+
/*
* Sets up the vmcs for emulated real mode.
*/
@@ -1146,13 +1195,6 @@ static int kvm_vcpu_setup(struct kvm_vcp

fx_init(vcpu);

-#define SEG_SETUP(seg) do { \
- vmcs_write16(GUEST_##seg##_SELECTOR, 0); \
- vmcs_writel(GUEST_##seg##_BASE, 0); \
- vmcs_write32(GUEST_##seg##_LIMIT, 0xffff); \
- vmcs_write32(GUEST_##seg##_AR_BYTES, 0x93); \
- } while (0)
-
/*
* GUEST_CS_BASE should really be 0xffff0000, but VT vm86 mode
* insists on having GUEST_CS_BASE == GUEST_CS_SELECTOR << 4. Sigh.
@@ -1162,11 +1204,11 @@ static int kvm_vcpu_setup(struct kvm_vcp
vmcs_write32(GUEST_CS_LIMIT, 0xffff);
vmcs_write32(GUEST_CS_AR_BYTES, 0x9b);

- SEG_SETUP(DS);
- SEG_SETUP(ES);
- SEG_SETUP(FS);
- SEG_SETUP(GS);
- SEG_SETUP(SS);
+ seg_setup(VCPU_SREG_DS);
+ seg_setup(VCPU_SREG_ES);
+ seg_setup(VCPU_SREG_FS);
+ seg_setup(VCPU_SREG_GS);
+ seg_setup(VCPU_SREG_SS);

vmcs_write16(GUEST_TR_SELECTOR, 0);
vmcs_writel(GUEST_TR_BASE, 0);
@@ -2900,6 +2942,28 @@ static int kvm_dev_ioctl_set_regs(struct
return 0;
}

+static void get_segment(struct kvm_segment *var, int seg)
+{
+ struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
+ u32 ar;
+
+ var->base = vmcs_readl(sf->base);
+ var->limit = vmcs_read32(sf->limit);
+ var->selector = vmcs_read16(sf->selector);
+ ar = vmcs_read32(sf->ar_bytes);
+ if (ar & AR_UNUSABLE_MASK)
+ ar = 0;
+ var->type = ar & 15;
+ var->s = (ar >> 4) & 1;
+ var->dpl = (ar >> 5) & 3;
+ var->present = (ar >> 7) & 1;
+ var->avl = (ar >> 12) & 1;
+ var->l = (ar >> 13) & 1;
+ var->db = (ar >> 14) & 1;
+ var->g = (ar >> 15) & 1;
+ var->unusable = (ar >> 16) & 1;
+}
+
static int kvm_dev_ioctl_get_sregs(struct kvm *kvm, struct kvm_sregs *sregs)
{
struct kvm_vcpu *vcpu;
@@ -2910,36 +2974,15 @@ static int kvm_dev_ioctl_get_sregs(struc
if (!vcpu)
return -ENOENT;

-#define get_segment(var, seg) \
- do { \
- u32 ar; \
- \
- sregs->var.base = vmcs_readl(GUEST_##seg##_BASE); \
- sregs->var.limit = vmcs_read32(GUEST_##seg##_LIMIT); \
- sregs->var.selector = vmcs_read16(GUEST_##seg##_SELECTOR); \
- ar = vmcs_read32(GUEST_##seg##_AR_BYTES); \
- if (ar & AR_UNUSABLE_MASK) ar = 0; \
- sregs->var.type = ar & 15; \
- sregs->var.s = (ar >> 4) & 1; \
- sregs->var.dpl = (ar >> 5) & 3; \
- sregs->var.present = (ar >> 7) & 1; \
- sregs->var.avl = (ar >> 12) & 1; \
- sregs->var.l = (ar >> 13) & 1; \
- sregs->var.db = (ar >> 14) & 1; \
- sregs->var.g = (ar >> 15) & 1; \
- sregs->var.unusable = (ar >> 16) & 1; \
- } while (0);
-
- get_segment(cs, CS);
- get_segment(ds, DS);
- get_segment(es, ES);
- get_segment(fs, FS);
- get_segment(gs, GS);
- get_segment(ss, SS);
-
- get_segment(tr, TR);
- get_segment(ldt, LDTR);
-#undef get_segment
+ get_segment(&sregs->cs, VCPU_SREG_CS);
+ get_segment(&sregs->ds, VCPU_SREG_DS);
+ get_segment(&sregs->es, VCPU_SREG_ES);
+ get_segment(&sregs->fs, VCPU_SREG_FS);
+ get_segment(&sregs->gs, VCPU_SREG_GS);
+ get_segment(&sregs->ss, VCPU_SREG_SS);
+
+ get_segment(&sregs->tr, VCPU_SREG_TR);
+ get_segment(&sregs->ldt, VCPU_SREG_LDTR);

#define get_dtable(var, table) \
sregs->var.limit = vmcs_read32(GUEST_##table##_LIMIT), \
@@ -2964,6 +3007,29 @@ static int kvm_dev_ioctl_get_sregs(struc
return 0;
}

+static void set_segment(struct kvm_segment *var, int seg)
+{
+ struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
+ u32 ar;
+
+ vmcs_writel(sf->base, var->base);
+ vmcs_write32(sf->limit, var->limit);
+ vmcs_write16(sf->selector, var->selector);
+ if (var->unusable)
+ ar = 1 << 16;
+ else {
+ ar = var->type & 15;
+ ar |= (var->s & 1) << 4;
+ ar |= (var->dpl & 3) << 5;
+ ar |= (var->present & 1) << 7;
+ ar |= (var->avl & 1) << 12;
+ ar |= (var->l & 1) << 13;
+ ar |= (var->db & 1) << 14;
+ ar |= (var->g & 1) << 15;
+ }
+ vmcs_write32(sf->ar_bytes, ar);
+}
+
static int kvm_dev_ioctl_set_sregs(struct kvm *kvm, struct kvm_sregs *sregs)
{
struct kvm_vcpu *vcpu;
@@ -2975,39 +3041,15 @@ static int kvm_dev_ioctl_set_sregs(struc
if (!vcpu)
return -ENOENT;

-#define set_segment(var, seg) \
- do { \
- u32 ar; \
- \
- vmcs_writel(GUEST_##seg##_BASE, sregs->var.base); \
- vmcs_write32(GUEST_##seg##_LIMIT, sregs->var.limit); \
- vmcs_write16(GUEST_##seg##_SELECTOR, sregs->var.selector); \
- if (sregs->var.unusable) { \
- ar = (1 << 16); \
- } else { \
- ar = (sregs->var.type & 15); \
- ar |= (sregs->var.s & 1) << 4; \
- ar |= (sregs->var.dpl & 3) << 5; \
- ar |= (sregs->var.present & 1) << 7; \
- ar |= (sregs->var.avl & 1) << 12; \
- ar |= (sregs->var.l & 1) << 13; \
- ar |= (sregs->var.db & 1) << 14; \
- ar |= (sregs->var.g & 1) << 15; \
- } \
- vmcs_write32(GUEST_##seg##_AR_BYTES, ar); \
- } while (0);
-
- set_segment(cs, CS);
- set_segment(ds, DS);
- set_segment(es, ES);
- set_segment(fs, FS);
- set_segment(gs, GS);
- set_segment(ss, SS);
-
- set_segment(tr, TR);
+ set_segment(&sregs->cs, VCPU_SREG_CS);
+ set_segment(&sregs->ds, VCPU_SREG_DS);
+ set_segment(&sregs->es, VCPU_SREG_ES);
+ set_segment(&sregs->fs, VCPU_SREG_FS);
+ set_segment(&sregs->gs, VCPU_SREG_GS);
+ set_segment(&sregs->ss, VCPU_SREG_SS);

- set_segment(ldt, LDTR);
-#undef set_segment
+ set_segment(&sregs->tr, VCPU_SREG_TR);
+ set_segment(&sregs->ldt, VCPU_SREG_LDTR);

#define set_dtable(var, table) \
vmcs_write32(GUEST_##table##_LIMIT, sregs->var.limit), \
-
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