Re: [PATCH] KVM: nVMX: expose INS/OUTS information support

From: Paolo Bonzini
Date: Mon Sep 05 2016 - 09:28:46 EST




On 04/09/2016 20:23, Jan Dakinevich wrote:
> Expose the feature to L1 hypervisor if host CPU supports it, since
> certain hypervisors requires it for own purposes.
>
> According to Intel SDM A.1, if CPU supports the feature,
> VMX_INSTRUCTION_INFO field of VMCS will contain detailed information
> about INS/OUTS instructions handling. This field is already copied to
> VMCS12 for L1 hypervisor (see prepare_vmcs12 routine) independently
> feature presence.
>
> Signed-off-by: Jan Dakinevich <jan.dakinevich@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index a4bb2bd..4fd22a6 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -939,6 +939,7 @@ static DEFINE_SPINLOCK(vmx_vpid_lock);
> static struct vmcs_config {
> int size;
> int order;
> + u32 basic_cap;
> u32 revision_id;
> u32 pin_based_exec_ctrl;
> u32 cpu_based_exec_ctrl;
> @@ -1215,6 +1216,11 @@ static inline bool cpu_has_vmx_ple(void)
> SECONDARY_EXEC_PAUSE_LOOP_EXITING;
> }
>
> +static inline bool cpu_has_vmx_basic_inout(void)
> +{
> + return (((u64)vmcs_config.basic_cap << 32) & VMX_BASIC_INOUT);
> +}
> +
> static inline bool cpu_need_virtualize_apic_accesses(struct kvm_vcpu *vcpu)
> {
> return flexpriority_enabled && lapic_in_kernel(vcpu);
> @@ -2877,6 +2883,8 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
> *pdata = VMCS12_REVISION | VMX_BASIC_TRUE_CTLS |
> ((u64)VMCS12_SIZE << VMX_BASIC_VMCS_SIZE_SHIFT) |
> (VMX_BASIC_MEM_TYPE_WB << VMX_BASIC_MEM_TYPE_SHIFT);
> + if (cpu_has_vmx_basic_inout())
> + *pdata |= VMX_BASIC_INOUT;
> break;
> case MSR_IA32_VMX_TRUE_PINBASED_CTLS:
> case MSR_IA32_VMX_PINBASED_CTLS:
> @@ -3458,6 +3466,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>
> vmcs_conf->size = vmx_msr_high & 0x1fff;
> vmcs_conf->order = get_order(vmcs_config.size);
> + vmcs_conf->basic_cap = vmx_msr_high;

Bits 32-44 are already stored in vmcs_conf->size, so please make this
"vmx_msr_high & ~0x1fff".

Otherwise looks fine!

Paolo

> vmcs_conf->revision_id = vmx_msr_low;
>
> vmcs_conf->pin_based_exec_ctrl = _pin_based_exec_control;
>