From: Vineeth Pillai <viremana@linux.microsoft.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>,
Lan Tianyu <Tianyu.Lan@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Wei Liu <wei.liu@kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"K. Y. Srinivasan" <kys@microsoft.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
viremana@linux.microsoft.com
Subject: Re: [PATCH v2 4/7] KVM: SVM: hyper-v: Nested enlightenments in VMCB
Date: Fri, 16 Apr 2021 13:07:00 -0400 [thread overview]
Message-ID: <4aaab6f9-7785-5c0a-4f9d-f972ec21888b@linux.microsoft.com> (raw)
In-Reply-To: <87v98m7gi4.fsf@vitty.brq.redhat.com>
On 4/16/2021 4:58 AM, Vitaly Kuznetsov wrote:
>
>> +
>> +#if IS_ENABLED(CONFIG_HYPERV)
>> +struct __packed hv_enlightenments {
>> + struct __packed hv_enlightenments_control {
>> + u32 nested_flush_hypercall:1;
>> + u32 msr_bitmap:1;
>> + u32 enlightened_npt_tlb: 1;
>> + u32 reserved:29;
>> + } hv_enlightenments_control;
>> + u32 hv_vp_id;
>> + u64 hv_vm_id;
>> + u64 partition_assist_page;
>> + u64 reserved;
>> +};
> Enlightened VMCS seems to have the same part:
>
> struct {
> u32 nested_flush_hypercall:1;
> u32 msr_bitmap:1;
> u32 reserved:30;
> } __packed hv_enlightenments_control;
> u32 hv_vp_id;
> u64 hv_vm_id;
> u64 partition_assist_page;
>
> Would it maybe make sense to unify these two (in case they are the same
> thing in Hyper-V, of course)?
They are very similar but, the individual bits are a bit different. SVM
struct has an
additional bit 'enlightened_npt_tlb'. There might be future changes as
well if new
enlightenments are designed for performance optimization. So I feel, we
can have
it as separate structs.
>>
>> +#define VMCB_ALL_CLEAN_MASK ( \
>> + (1U << VMCB_INTERCEPTS) | (1U << VMCB_PERM_MAP) | \
>> + (1U << VMCB_ASID) | (1U << VMCB_INTR) | \
>> + (1U << VMCB_NPT) | (1U << VMCB_CR) | (1U << VMCB_DR) | \
>> + (1U << VMCB_DT) | (1U << VMCB_SEG) | (1U << VMCB_CR2) | \
>> + (1U << VMCB_LBR) | (1U << VMCB_AVIC) \
>> + )
> What if we preserve VMCB_DIRTY_MAX and drop this newly introduced
> VMCB_ALL_CLEAN_MASK (which basically lists all the members of the enum
> above)? '1 << VMCB_DIRTY_MAX' can still work. (If the 'VMCB_DIRTY_MAX'
> name becomes misleading we can e.g. rename it to VMCB_NATIVE_DIRTY_MAX
> or something but I'm not sure it's worth it)
I thought of keeping this code because, if we have non-contiguous bits
in future, we
would need this kinda logic anyways. But I get your point. Will revert this.
>
>> +#if IS_ENABLED(CONFIG_HYPERV)
>> +#define VMCB_HYPERV_CLEAN_MASK (1U << VMCB_HV_NESTED_ENLIGHTENMENTS)
>> +#endif
> VMCB_HYPERV_CLEAN_MASK is a single bit, why do we need it at all
> (BIT(VMCB_HV_NESTED_ENLIGHTENMENTS) is not super long)
Agreed. Will change it in next revision.
Thanks,
Vineeth
next prev parent reply other threads:[~2021-04-16 17:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 13:43 [PATCH v2 0/7] Hyper-V nested virt enlightenments for SVM Vineeth Pillai
2021-04-15 13:43 ` [PATCH v2 1/7] hyperv: Detect Nested virtualization support " Vineeth Pillai
2021-04-16 8:26 ` Vitaly Kuznetsov
2021-04-16 16:10 ` Vineeth Pillai
2021-04-15 13:43 ` [PATCH v2 2/7] hyperv: SVM enlightened TLB flush support flag Vineeth Pillai
2021-04-21 10:00 ` Wei Liu
2021-04-21 11:15 ` Vineeth Pillai
2021-04-21 13:20 ` Wei Liu
2021-04-15 13:43 ` [PATCH v2 3/7] KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx Vineeth Pillai
2021-04-16 8:36 ` Vitaly Kuznetsov
2021-04-16 8:40 ` Paolo Bonzini
2021-04-16 16:39 ` Vineeth Pillai
2021-04-20 15:57 ` Vitaly Kuznetsov
2021-04-15 13:43 ` [PATCH v2 4/7] KVM: SVM: hyper-v: Nested enlightenments in VMCB Vineeth Pillai
2021-04-16 8:58 ` Vitaly Kuznetsov
2021-04-16 17:07 ` Vineeth Pillai [this message]
2021-04-15 13:43 ` [PATCH v2 5/7] KVM: SVM: hyper-v: Remote TLB flush for SVM Vineeth Pillai
2021-04-16 9:04 ` Vitaly Kuznetsov
2021-04-16 17:26 ` Vineeth Pillai
2021-04-21 14:03 ` Vineeth Pillai
2021-04-15 13:43 ` [PATCH v2 6/7] KVM: SVM: hyper-v: Enlightened MSR-Bitmap support Vineeth Pillai
2021-04-15 13:43 ` [PATCH v2 7/7] KVM: SVM: hyper-v: Direct Virtual Flush support Vineeth Pillai
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