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Fix incorrect VMX_ENTRY_CONTROLS loading. #225

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Aug 16, 2019
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Fix incorrect VMX_ENTRY_CONTROLS loading. #225

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Fix incorrect VMX_ENTRY_CONTROLS loading. 
There exists some issue when programming VMX_ENTRY_CONTROLS and GUEST_EFER:
- ENTRY_CONTROL_LONG_MODE_GUEST has no chance to clear.
- vmwrite_efer() called by vmwrite_cr() will check vmx field before
vmx field gets updated, and itself will also program VMX_ENTRY_CONTROLS,
which may cause incorrect VMX_ENTRY_CONTROLS programmed.
- vmx filed entry_ctls_base and entry_ctls are loaded from vmcs in:
vcpu_create()->vcpu_prepare()->fill_common_vmcs()->load_vmcs_common().
When vmwrite_cr() and vmwrite_efer() write a dirty VMX_ENTRY_CONTROLS,
it only updates vmx field entry_ctls, but it compares with value of
entry_ctls_base for dirty check, which may cause reduntant or miss
programming to VMX_ENTRY_CONTROLS.

Below changes are made:
- Add the missing clear of ENTRY_CONTROL_LONG_MODE_GUEST.
- Move vmwrite_efer() to last of vmwrite_cr() after VMX_ENTRY_CONTROLS
  programmed.
- Remove unnecessary entry_ctls_base in vmx field.

Signed-off-by: Colin Xu <[email protected]>
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@coxuintel
coxuintel committed Aug 7, 2019
commit 834ffc191d8f78c468f36187ac278a9c32aa0a1d
3 changes: 1 addition & 2 deletions core/cpu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -624,8 +624,7 @@ void load_vmcs_common(struct vcpu_t *vcpu)

vmx(vcpu, exc_bitmap) = vmx(vcpu, exc_bitmap_base) = vmread(
vcpu, VMX_EXCEPTION_BITMAP);
vmx(vcpu, entry_ctls) = vmx(vcpu, entry_ctls_base) = vmread(
vcpu, VMX_ENTRY_CONTROLS);
vmx(vcpu, entry_ctls) = vmread(vcpu, VMX_ENTRY_CONTROLS);
vmx(vcpu, exit_ctls) = vmx(vcpu, exit_ctls_base) = vmread(
vcpu, VMX_EXIT_CONTROLS);

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1 change: 0 additions & 1 deletion core/include/vcpu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,6 @@ struct vcpu_vmx_data {
uint32_t pin_ctls_base;
uint32_t pcpu_ctls_base;
uint32_t scpu_ctls_base;
uint32_t entry_ctls_base;
uint32_t exc_bitmap_base;
uint32_t exit_ctls_base;

Expand Down
20 changes: 10 additions & 10 deletions core/vcpu.c
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Expand Up @@ -1900,7 +1900,7 @@ static void vmwrite_cr(struct vcpu_t *vcpu)
struct vcpu_state_t *state = vcpu->state;
struct per_cpu_data *cpu = current_cpu_data();

uint32_t entry_ctls = vmx(vcpu, entry_ctls_base);
uint32_t entry_ctls = vmx(vcpu, entry_ctls);
uint32_t pcpu_ctls = vmx(vcpu, pcpu_ctls_base);
uint32_t scpu_ctls = vmx(vcpu, scpu_ctls_base);
uint32_t exc_bitmap = vmx(vcpu, exc_bitmap_base);
Expand Down Expand Up @@ -2017,16 +2017,10 @@ static void vmwrite_cr(struct vcpu_t *vcpu)
if ((state->_cr4 & CR4_PAE) && (state->_cr0 & CR0_PG) &&
(state->_cr0 & CR0_PE)) {
entry_ctls |= ENTRY_CONTROL_LOAD_EFER;
vmx(vcpu, entry_ctls) |= ENTRY_CONTROL_LOAD_EFER;
} else {
entry_ctls &= ~ENTRY_CONTROL_LOAD_EFER;
vmx(vcpu, entry_ctls) &= ~ENTRY_CONTROL_LOAD_EFER;
}

vmwrite_efer(vcpu);
if (state->_efer & IA32_EFER_LMA) {
entry_ctls |= ENTRY_CONTROL_LONG_MODE_GUEST;
}
if (pcpu_ctls != vmx(vcpu, pcpu_ctls)) {
vmx(vcpu, pcpu_ctls) = pcpu_ctls;
vcpu->pcpu_ctls_dirty = 1;
Expand All @@ -2041,6 +2035,8 @@ static void vmwrite_cr(struct vcpu_t *vcpu)
if (entry_ctls != vmx(vcpu, entry_ctls)) {
vmwrite(vcpu, VMX_ENTRY_CONTROLS, vmx(vcpu, entry_ctls) = entry_ctls);
}

vmwrite_efer(vcpu);
}

static void vcpu_enter_fpu_state(struct vcpu_t *vcpu)
Expand Down Expand Up @@ -3489,14 +3485,14 @@ static int handle_msr_read(struct vcpu_t *vcpu, uint32_t msr, uint64_t *val)
static void vmwrite_efer(struct vcpu_t *vcpu)
{
struct vcpu_state_t *state = vcpu->state;
uint32_t entry_ctls = vmx(vcpu, entry_ctls);

if ((state->_cr0 & CR0_PG) && (state->_efer & IA32_EFER_LME)) {
state->_efer |= IA32_EFER_LMA;

vmwrite(vcpu, VMX_ENTRY_CONTROLS, vmread(vcpu, VMX_ENTRY_CONTROLS) |
ENTRY_CONTROL_LONG_MODE_GUEST);
entry_ctls |= ENTRY_CONTROL_LONG_MODE_GUEST;
} else {
state->_efer &= ~IA32_EFER_LMA;
entry_ctls &= ~ENTRY_CONTROL_LONG_MODE_GUEST;
}

if (vmx(vcpu, entry_ctls) & ENTRY_CONTROL_LOAD_EFER) {
Expand All @@ -3508,6 +3504,10 @@ static void vmwrite_efer(struct vcpu_t *vcpu)

vmwrite(vcpu, GUEST_EFER, guest_efer);
}

if (entry_ctls != vmx(vcpu, entry_ctls)) {
vmwrite(vcpu, VMX_ENTRY_CONTROLS, vmx(vcpu, entry_ctls) = entry_ctls);
}
}

static int misc_msr_write(struct vcpu_t *vcpu, uint32_t msr, uint64_t val)
Expand Down