lkml.org 
[lkml]   [2019]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH v7 2/3] KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL
On Fri, Jul 12, 2019 at 04:29:06PM +0800, Tao Xu wrote:
> diff --git a/arch/x86/kernel/cpu/umwait.c b/arch/x86/kernel/cpu/umwait.c
> index 6a204e7336c1..631152a67c6e 100644
> --- a/arch/x86/kernel/cpu/umwait.c
> +++ b/arch/x86/kernel/cpu/umwait.c
> @@ -15,7 +15,8 @@
> * Cache IA32_UMWAIT_CONTROL MSR. This is a systemwide control. By default,
> * umwait max time is 100000 in TSC-quanta and C0.2 is enabled
> */
> -static u32 umwait_control_cached = UMWAIT_CTRL_VAL(100000, UMWAIT_C02_ENABLE);
> +u32 umwait_control_cached = UMWAIT_CTRL_VAL(100000, UMWAIT_C02_ENABLE);
> +EXPORT_SYMBOL_GPL(umwait_control_cached);

It'd probably be better to add an accessor to expose umwait_control_cached
given that umwait.c is using {READ,WRITE}_ONCE() and there shouldn't be a
need to write it outside of umwait.c.

> /*
> * Serialize access to umwait_control_cached and IA32_UMWAIT_CONTROL MSR in
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index f411c9ae5589..0787f140d155 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1676,6 +1676,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> #endif
> case MSR_EFER:
> return kvm_get_msr_common(vcpu, msr_info);
> + case MSR_IA32_UMWAIT_CONTROL:
> + if (!msr_info->host_initiated && !vmx_has_waitpkg(vmx))
> + return 1;
> +
> + msr_info->data = vmx->msr_ia32_umwait_control;
> + break;
> case MSR_IA32_SPEC_CTRL:
> if (!msr_info->host_initiated &&
> !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
> @@ -1838,6 +1844,16 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> return 1;
> vmcs_write64(GUEST_BNDCFGS, data);
> break;
> + case MSR_IA32_UMWAIT_CONTROL:
> + if (!msr_info->host_initiated && !vmx_has_waitpkg(vmx))
> + return 1;
> +
> + /* The reserved bit IA32_UMWAIT_CONTROL[1] should be zero */
> + if (data & BIT_ULL(1))
> + return 1;
> +
> + vmx->msr_ia32_umwait_control = data;

The SDM only defines bits 31:0, and the kernel uses a u32 to cache its
value. I assume bits 63:32 are reserved? I'm guessing we also need an
SDM update...

> + break;
> case MSR_IA32_SPEC_CTRL:
> if (!msr_info->host_initiated &&
> !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
> @@ -4139,6 +4155,8 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> vmx->rmode.vm86_active = 0;
> vmx->spec_ctrl = 0;
>
> + vmx->msr_ia32_umwait_control = 0;
> +
> vcpu->arch.microcode_version = 0x100000000ULL;
> vmx->vcpu.arch.regs[VCPU_REGS_RDX] = get_rdx_init_val();
> kvm_set_cr8(vcpu, 0);
> @@ -6352,6 +6370,19 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
> msrs[i].host, false);
> }
>

\
 
 \ /
  Last update: 2019-07-12 17:52    [W:0.061 / U:0.016 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site