Re: [PATCH 2/3] Add HYPER-V apic access MSRs.

[Avi Kivity <avi@redhat.com>]

On 01/13/2010 03:59 PM, Gleb Natapov wrote:
> Signed-off-by: Gleb Natapov<gleb@redhat.com>
> Signed-off-by: Vadim Rozenfeld<vrozenfe@redhat.com>
> ---
>   arch/x86/include/asm/kvm_host.h |    2 +
>   arch/x86/kvm/lapic.c            |   53 +++++++++++++++++++++++++++++++++++++++
>   arch/x86/kvm/lapic.h            |    8 ++++++
>   arch/x86/kvm/x86.c              |   34 ++++++++++++++++++++++---
>   include/linux/kvm.h             |    1 +
>   5 files changed, 94 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 7bfd468..4d82c52 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -362,6 +362,8 @@ struct kvm_vcpu_arch {
>   	/* used for guest single stepping over the given code position */
>   	u16 singlestep_cs;
>   	unsigned long singlestep_rip;
> +	/* fields used by HYPER-V emulation */
> +	u64 hv_vapic;
>   };
>
>   struct kvm_mem_alias {
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index ba8c045..063963f 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1246,3 +1246,56 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
>
>   	return 0;
>   }
> +
> +static u32 kvm_hv_vapic_msr2reg(u32 msr)
> +{
> +	u32 reg;
> +	switch (msr) {
> +	case HV_X64_MSR_EOI:
> +		reg = APIC_EOI;
> +		break;
> +	case HV_X64_MSR_ICR:
> +		reg = APIC_ICR;
> +		break;
> +	case HV_X64_MSR_TPR:
> +		reg = APIC_TASKPRI;
> +		break;
> +	default:
> +		reg = -1;
> +		break;
> +	}
> +
> +	return reg;
> +}
> +
> +int kvm_hv_vapic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> +{
> +	struct kvm_lapic *apic = vcpu->arch.apic;
> +	u32 reg = kvm_hv_vapic_msr2reg(msr);
> +
> +	if (!irqchip_in_kernel(vcpu->kvm))
> +		return 1;
> +
> +	/* if this is ICR write vector before command */
> +	if (reg == APIC_ICR)
> +		apic_reg_write(apic, APIC_ICR2, (u32)(data>>  32));
> +	return apic_reg_write(apic, reg, (u32)data);
> +}
> +
> +int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
> +{
> +	struct kvm_lapic *apic = vcpu->arch.apic;
> +	u32 reg = kvm_hv_vapic_msr2reg(msr), low, high = 0;
> +
> +	if (!irqchip_in_kernel(vcpu->kvm))
> +		return 1;
> +
> +	if (apic_reg_read(apic, reg, 4,&low))
> +		return 1;
> +	if (reg == APIC_ICR)
> +		apic_reg_read(apic, APIC_ICR2, 4,&high);
> +
> +	*data = (((u64)high)<<  32) | low;
> +
> +	return 0;
> +}
>    

I think it's cleaner to put all this into the (set_msr and get_msr).  
You're just converting register numbers back and forth, while they are 
known at the call site.

>   #endif
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 6972b2b..e058898 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -629,7 +629,8 @@ static u32 msrs_to_save[] = {
>   	MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
>   #endif
>   	MSR_IA32_TSC, MSR_IA32_PERF_STATUS, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
> -	HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL
> +	HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
> +	HV_X64_MSR_APIC_ASSIST_PAGE
>   };
>    

, at the end.

>
>   static unsigned num_msrs_to_save;
> @@ -1061,10 +1062,30 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
>
>   static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
>   {
> -	pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x data 0x%llx\n",
> -		  msr, data);
> +	switch (msr) {
> +	case HV_X64_MSR_APIC_ASSIST_PAGE: {
> +		unsigned long addr;
> +		vcpu->arch.hv_vapic = data;
> +		if(!kvm_hv_vapic_enabled(vcpu))
> +			break;
>    

Space after if.

> +		addr = gfn_to_hva(vcpu->kvm, data>>
> +				  HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT);
> +		if (kvm_is_error_hva(addr))
> +			return 1;
>    

But the spec actually permits addresses outside RAM?

> +		memset((void*)addr, 0, PAGE_SIZE);
>    

clear_user_page()!

> +		break;
> +	}
> +	case HV_X64_MSR_EOI:
> +	case HV_X64_MSR_ICR:
> +	case HV_X64_MSR_TPR:
> +		return kvm_hv_vapic_msr_write(vcpu, msr, data);
>    

Here, just call the apic function with the known apic register number.

-- 
error compiling committee.c: too many arguments to function