[PATCH] KVM: VMX: fix read/write sizes of VMCS fields

[PATCH] KVM: VMX: fix read/write sizes of VMCS fields

[Paolo Bonzini]

In theory this should have broken EPT on 32-bit kernels (due to
reading the high part of natural-width field GUEST_CR3).  Not sure
if no one noticed or the processor behaves differently from the
documentation.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c39737ff0581..b1af1e48070b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4868,7 +4868,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
 	seg_setup(VCPU_SREG_CS);
 	vmcs_write16(GUEST_CS_SELECTOR, 0xf000);
-	vmcs_write32(GUEST_CS_BASE, 0xffff0000);
+	vmcs_writel(GUEST_CS_BASE, 0xffff0000ul);
 
 	seg_setup(VCPU_SREG_DS);
 	seg_setup(VCPU_SREG_ES);
@@ -4904,7 +4904,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
 	vmcs_write32(GUEST_ACTIVITY_STATE, GUEST_ACTIVITY_ACTIVE);
 	vmcs_write32(GUEST_INTERRUPTIBILITY_INFO, 0);
-	vmcs_write32(GUEST_PENDING_DBG_EXCEPTIONS, 0);
+	vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS, 0);
 
 	setup_msrs(vmx);
 
@@ -7893,7 +7893,7 @@ static void dump_vmcs(void)
 	u32 pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
 	u32 secondary_exec_control = 0;
 	unsigned long cr4 = vmcs_readl(GUEST_CR4);
-	u64 efer = vmcs_readl(GUEST_IA32_EFER);
+	u64 efer = vmcs_read64(GUEST_IA32_EFER);
 	int i, n;
 
 	if (cpu_has_secondary_exec_ctrls())
@@ -10159,7 +10159,7 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 	 * Additionally, restore L2's PDPTR to vmcs12.
 	 */
 	if (enable_ept) {
-		vmcs12->guest_cr3 = vmcs_read64(GUEST_CR3);
+		vmcs12->guest_cr3 = vmcs_readl(GUEST_CR3);
 		vmcs12->guest_pdptr0 = vmcs_read64(GUEST_PDPTR0);
 		vmcs12->guest_pdptr1 = vmcs_read64(GUEST_PDPTR1);
 		vmcs12->guest_pdptr2 = vmcs_read64(GUEST_PDPTR2);
-- 
1.8.3.1

Re: [PATCH] KVM: VMX: fix read/write sizes of VMCS fields

[Yang Zhang]

On 2015/12/3 23:11, Paolo Bonzini wrote:
> In theory this should have broken EPT on 32-bit kernels (due to
> reading the high part of natural-width field GUEST_CR3).  Not sure
> if no one noticed or the processor behaves differently from the
> documentation.

It seems we will check the success of vmcs_write but not vmcs_read. 
Shouldn't check the vmcs_read?

>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   arch/x86/kvm/vmx.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index c39737ff0581..b1af1e48070b 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -4868,7 +4868,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>
>   	seg_setup(VCPU_SREG_CS);
>   	vmcs_write16(GUEST_CS_SELECTOR, 0xf000);
> -	vmcs_write32(GUEST_CS_BASE, 0xffff0000);
> +	vmcs_writel(GUEST_CS_BASE, 0xffff0000ul);
>
>   	seg_setup(VCPU_SREG_DS);
>   	seg_setup(VCPU_SREG_ES);
> @@ -4904,7 +4904,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>
>   	vmcs_write32(GUEST_ACTIVITY_STATE, GUEST_ACTIVITY_ACTIVE);
>   	vmcs_write32(GUEST_INTERRUPTIBILITY_INFO, 0);
> -	vmcs_write32(GUEST_PENDING_DBG_EXCEPTIONS, 0);
> +	vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS, 0);
>
>   	setup_msrs(vmx);
>
> @@ -7893,7 +7893,7 @@ static void dump_vmcs(void)
>   	u32 pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
>   	u32 secondary_exec_control = 0;
>   	unsigned long cr4 = vmcs_readl(GUEST_CR4);
> -	u64 efer = vmcs_readl(GUEST_IA32_EFER);
> +	u64 efer = vmcs_read64(GUEST_IA32_EFER);
>   	int i, n;
>
>   	if (cpu_has_secondary_exec_ctrls())
> @@ -10159,7 +10159,7 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
>   	 * Additionally, restore L2's PDPTR to vmcs12.
>   	 */
>   	if (enable_ept) {
> -		vmcs12->guest_cr3 = vmcs_read64(GUEST_CR3);
> +		vmcs12->guest_cr3 = vmcs_readl(GUEST_CR3);
>   		vmcs12->guest_pdptr0 = vmcs_read64(GUEST_PDPTR0);
>   		vmcs12->guest_pdptr1 = vmcs_read64(GUEST_PDPTR1);
>   		vmcs12->guest_pdptr2 = vmcs_read64(GUEST_PDPTR2);
>



-- 
best regards
yang