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KVM: emulator: Fix io permission checking for 64bit guest

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Current implementation truncates upper 32bit of TR base address during IO
permission bitmap check. The patch fixes this.

Reported-and-tested-by: Francis Moreau <francis.moro@gmail.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Gleb Natapov 2011-03-07 14:55:06 +02:00 committed by Marcelo Tosatti
parent 831ca6093c
commit 5601d05b8c
3 changed files with 35 additions and 21 deletions
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4
arch/x86/include/asm/kvm_emulate.h
View File

@ -142,9 +142,9 @@ struct x86_emulate_ops {
int (*pio_out_emulated)(int size, unsigned short port, const void *val,
unsigned int count, struct kvm_vcpu *vcpu);
bool (*get_cached_descriptor)(struct desc_struct *desc,
bool (*get_cached_descriptor)(struct desc_struct *desc, u32 *base3,
int seg, struct kvm_vcpu *vcpu);
void (*set_cached_descriptor)(struct desc_struct *desc,
void (*set_cached_descriptor)(struct desc_struct *desc, u32 base3,
int seg, struct kvm_vcpu *vcpu);
u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);

37
arch/x86/kvm/emulate.c
View File

@ -878,7 +878,8 @@ static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt,
if (selector & 1 << 2) {
struct desc_struct desc;
memset (dt, 0, sizeof *dt);
if (!ops->get_cached_descriptor(&desc, VCPU_SREG_LDTR, ctxt->vcpu))
if (!ops->get_cached_descriptor(&desc, NULL, VCPU_SREG_LDTR,
ctxt->vcpu))
return;
dt->size = desc_limit_scaled(&desc); /* what if limit > 65535? */
@ -930,6 +931,7 @@ static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
return ret;
}
/* Does not support long mode */
static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops,
u16 selector, int seg)
@ -1041,7 +1043,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
}
load:
ops->set_segment_selector(selector, seg, ctxt->vcpu);
ops->set_cached_descriptor(&seg_desc, seg, ctxt->vcpu);
ops->set_cached_descriptor(&seg_desc, 0, seg, ctxt->vcpu);
return X86EMUL_CONTINUE;
exception:
emulate_exception(ctxt, err_vec, err_code, true);
@ -1561,7 +1563,7 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt,
struct desc_struct *ss)
{
memset(cs, 0, sizeof(struct desc_struct));
ops->get_cached_descriptor(cs, VCPU_SREG_CS, ctxt->vcpu);
ops->get_cached_descriptor(cs, NULL, VCPU_SREG_CS, ctxt->vcpu);
memset(ss, 0, sizeof(struct desc_struct));
cs->l = 0; /* will be adjusted later */
@ -1608,9 +1610,9 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
cs.d = 0;
cs.l = 1;
}
ops->set_cached_descriptor(&cs, VCPU_SREG_CS, ctxt->vcpu);
ops->set_cached_descriptor(&cs, 0, VCPU_SREG_CS, ctxt->vcpu);
ops->set_segment_selector(cs_sel, VCPU_SREG_CS, ctxt->vcpu);
ops->set_cached_descriptor(&ss, VCPU_SREG_SS, ctxt->vcpu);
ops->set_cached_descriptor(&ss, 0, VCPU_SREG_SS, ctxt->vcpu);
ops->set_segment_selector(ss_sel, VCPU_SREG_SS, ctxt->vcpu);
c->regs[VCPU_REGS_RCX] = c->eip;
@ -1680,9 +1682,9 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
cs.l = 1;
}
ops->set_cached_descriptor(&cs, VCPU_SREG_CS, ctxt->vcpu);
ops->set_cached_descriptor(&cs, 0, VCPU_SREG_CS, ctxt->vcpu);
ops->set_segment_selector(cs_sel, VCPU_SREG_CS, ctxt->vcpu);
ops->set_cached_descriptor(&ss, VCPU_SREG_SS, ctxt->vcpu);
ops->set_cached_descriptor(&ss, 0, VCPU_SREG_SS, ctxt->vcpu);
ops->set_segment_selector(ss_sel, VCPU_SREG_SS, ctxt->vcpu);
ops->get_msr(ctxt->vcpu, MSR_IA32_SYSENTER_EIP, &msr_data);
@ -1737,9 +1739,9 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
cs_sel |= SELECTOR_RPL_MASK;
ss_sel |= SELECTOR_RPL_MASK;
ops->set_cached_descriptor(&cs, VCPU_SREG_CS, ctxt->vcpu);
ops->set_cached_descriptor(&cs, 0, VCPU_SREG_CS, ctxt->vcpu);
ops->set_segment_selector(cs_sel, VCPU_SREG_CS, ctxt->vcpu);
ops->set_cached_descriptor(&ss, VCPU_SREG_SS, ctxt->vcpu);
ops->set_cached_descriptor(&ss, 0, VCPU_SREG_SS, ctxt->vcpu);
ops->set_segment_selector(ss_sel, VCPU_SREG_SS, ctxt->vcpu);
c->eip = c->regs[VCPU_REGS_RDX];
@ -1765,24 +1767,29 @@ static bool emulator_io_port_access_allowed(struct x86_emulate_ctxt *ctxt,
u16 port, u16 len)
{
struct desc_struct tr_seg;
u32 base3;
int r;
u16 io_bitmap_ptr;
u8 perm, bit_idx = port & 0x7;
unsigned mask = (1 << len) - 1;
unsigned long base;
ops->get_cached_descriptor(&tr_seg, VCPU_SREG_TR, ctxt->vcpu);
ops->get_cached_descriptor(&tr_seg, &base3, VCPU_SREG_TR, ctxt->vcpu);
if (!tr_seg.p)
return false;
if (desc_limit_scaled(&tr_seg) < 103)
return false;
r = ops->read_std(get_desc_base(&tr_seg) + 102, &io_bitmap_ptr, 2,
ctxt->vcpu, NULL);
base = get_desc_base(&tr_seg);
#ifdef CONFIG_X86_64
base |= ((u64)base3) << 32;
#endif
r = ops->read_std(base + 102, &io_bitmap_ptr, 2, ctxt->vcpu, NULL);
if (r != X86EMUL_CONTINUE)
return false;
if (io_bitmap_ptr + port/8 > desc_limit_scaled(&tr_seg))
return false;
r = ops->read_std(get_desc_base(&tr_seg) + io_bitmap_ptr + port/8,
&perm, 1, ctxt->vcpu, NULL);
r = ops->read_std(base + io_bitmap_ptr + port/8, &perm, 1, ctxt->vcpu,
NULL);
if (r != X86EMUL_CONTINUE)
return false;
if ((perm >> bit_idx) & mask)
@ -2127,7 +2134,7 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt,
}
ops->set_cr(0, ops->get_cr(0, ctxt->vcpu) | X86_CR0_TS, ctxt->vcpu);
ops->set_cached_descriptor(&next_tss_desc, VCPU_SREG_TR, ctxt->vcpu);
ops->set_cached_descriptor(&next_tss_desc, 0, VCPU_SREG_TR, ctxt->vcpu);
ops->set_segment_selector(tss_selector, VCPU_SREG_TR, ctxt->vcpu);
if (has_error_code) {

15
arch/x86/kvm/x86.c
View File

@ -4162,8 +4162,8 @@ static unsigned long emulator_get_cached_segment_base(int seg,
return get_segment_base(vcpu, seg);
}
static bool emulator_get_cached_descriptor(struct desc_struct *desc, int seg,
struct kvm_vcpu *vcpu)
static bool emulator_get_cached_descriptor(struct desc_struct *desc, u32 *base3,
int seg, struct kvm_vcpu *vcpu)
{
struct kvm_segment var;
@ -4176,6 +4176,10 @@ static bool emulator_get_cached_descriptor(struct desc_struct *desc, int seg,
var.limit >>= 12;
set_desc_limit(desc, var.limit);
set_desc_base(desc, (unsigned long)var.base);
#ifdef CONFIG_X86_64
if (base3)
*base3 = var.base >> 32;
#endif
desc->type = var.type;
desc->s = var.s;
desc->dpl = var.dpl;
@ -4188,8 +4192,8 @@ static bool emulator_get_cached_descriptor(struct desc_struct *desc, int seg,
return true;
}
static void emulator_set_cached_descriptor(struct desc_struct *desc, int seg,
struct kvm_vcpu *vcpu)
static void emulator_set_cached_descriptor(struct desc_struct *desc, u32 base3,
int seg, struct kvm_vcpu *vcpu)
{
struct kvm_segment var;
@ -4197,6 +4201,9 @@ static void emulator_set_cached_descriptor(struct desc_struct *desc, int seg,
kvm_get_segment(vcpu, &var, seg);
var.base = get_desc_base(desc);
#ifdef CONFIG_X86_64
var.base |= ((u64)base3) << 32;
#endif
var.limit = get_desc_limit(desc);
if (desc->g)
var.limit = (var.limit << 12) | 0xfff;