* [PATCH] KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd()
@ 2020-09-24 18:04 Sean Christopherson
2020-09-25 9:59 ` Vitaly Kuznetsov
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2020-09-24 18:04 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
Explicitly check that kvm_x86_ops.tlb_remote_flush() points at Hyper-V's
implementation for PV flushing instead of assuming that a non-NULL
implementation means running on Hyper-V. Wrap the related logic in
ifdeffery as hv_remote_flush_tlb() is defined iff CONFIG_HYPERV!=n.
Short term, the explicit check makes it more obvious why a non-NULL
tlb_remote_flush() triggers EPTP shenanigans. Long term, this will
allow TDX to define its own implementation of tlb_remote_flush() without
running afoul of Hyper-V.
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/vmx/vmx.c | 7 +++++--
arch/x86/kvm/vmx/vmx.h | 2 ++
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 6f9a0c6d5dc5..a56fa9451b84 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3073,14 +3073,15 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, unsigned long pgd,
eptp = construct_eptp(vcpu, pgd, pgd_level);
vmcs_write64(EPT_POINTER, eptp);
- if (kvm_x86_ops.tlb_remote_flush) {
+#if IS_ENABLED(CONFIG_HYPERV)
+ if (kvm_x86_ops.tlb_remote_flush == hv_remote_flush_tlb) {
spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock);
to_vmx(vcpu)->ept_pointer = eptp;
to_kvm_vmx(kvm)->ept_pointers_match
= EPT_POINTERS_CHECK;
spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
}
-
+#endif
if (!enable_unrestricted_guest && !is_paging(vcpu))
guest_cr3 = to_kvm_vmx(kvm)->ept_identity_map_addr;
else if (test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
@@ -6956,7 +6957,9 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
static int vmx_vm_init(struct kvm *kvm)
{
+#if IS_ENABLED(CONFIG_HYPERV)
spin_lock_init(&to_kvm_vmx(kvm)->ept_pointer_lock);
+#endif
if (!ple_gap)
kvm->arch.pause_in_guest = true;
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index d7ec66db5eb8..51107b7309bc 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -316,8 +316,10 @@ struct kvm_vmx {
bool ept_identity_pagetable_done;
gpa_t ept_identity_map_addr;
+#if IS_ENABLED(CONFIG_HYPERV)
enum ept_pointers_status ept_pointers_match;
spinlock_t ept_pointer_lock;
+#endif
};
bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
--
2.28.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd()
2020-09-24 18:04 [PATCH] KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd() Sean Christopherson
@ 2020-09-25 9:59 ` Vitaly Kuznetsov
2020-09-25 16:24 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: Vitaly Kuznetsov @ 2020-09-25 9:59 UTC (permalink / raw)
To: Sean Christopherson, Paolo Bonzini
Cc: Sean Christopherson, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
Sean Christopherson <sean.j.christopherson@intel.com> writes:
> Explicitly check that kvm_x86_ops.tlb_remote_flush() points at Hyper-V's
> implementation for PV flushing instead of assuming that a non-NULL
> implementation means running on Hyper-V. Wrap the related logic in
> ifdeffery as hv_remote_flush_tlb() is defined iff CONFIG_HYPERV!=n.
>
> Short term, the explicit check makes it more obvious why a non-NULL
> tlb_remote_flush() triggers EPTP shenanigans. Long term, this will
> allow TDX to define its own implementation of tlb_remote_flush() without
> running afoul of Hyper-V.
>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 7 +++++--
> arch/x86/kvm/vmx/vmx.h | 2 ++
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 6f9a0c6d5dc5..a56fa9451b84 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -3073,14 +3073,15 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, unsigned long pgd,
> eptp = construct_eptp(vcpu, pgd, pgd_level);
> vmcs_write64(EPT_POINTER, eptp);
>
> - if (kvm_x86_ops.tlb_remote_flush) {
> +#if IS_ENABLED(CONFIG_HYPERV)
> + if (kvm_x86_ops.tlb_remote_flush == hv_remote_flush_tlb) {
> spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock);
> to_vmx(vcpu)->ept_pointer = eptp;
> to_kvm_vmx(kvm)->ept_pointers_match
> = EPT_POINTERS_CHECK;
> spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
> }
> -
> +#endif
> if (!enable_unrestricted_guest && !is_paging(vcpu))
> guest_cr3 = to_kvm_vmx(kvm)->ept_identity_map_addr;
> else if (test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
> @@ -6956,7 +6957,9 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
>
> static int vmx_vm_init(struct kvm *kvm)
> {
> +#if IS_ENABLED(CONFIG_HYPERV)
> spin_lock_init(&to_kvm_vmx(kvm)->ept_pointer_lock);
> +#endif
>
> if (!ple_gap)
> kvm->arch.pause_in_guest = true;
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index d7ec66db5eb8..51107b7309bc 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -316,8 +316,10 @@ struct kvm_vmx {
> bool ept_identity_pagetable_done;
> gpa_t ept_identity_map_addr;
>
> +#if IS_ENABLED(CONFIG_HYPERV)
> enum ept_pointers_status ept_pointers_match;
> spinlock_t ept_pointer_lock;
> +#endif
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
In case ept_pointers_match/ept_pointer_lock are useless for TDX we may
want to find better names for them to make it clear this is a Hyper-V
thingy (e.g. something like hv_tlb_ept_match/hv_tlb_ept_lock).
> };
>
> bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
--
Vitaly
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd()
2020-09-25 9:59 ` Vitaly Kuznetsov
@ 2020-09-25 16:24 ` Sean Christopherson
0 siblings, 0 replies; 3+ messages in thread
From: Sean Christopherson @ 2020-09-25 16:24 UTC (permalink / raw)
To: Vitaly Kuznetsov
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm, linux-kernel
On Fri, Sep 25, 2020 at 11:59:00AM +0200, Vitaly Kuznetsov wrote:
> Sean Christopherson <sean.j.christopherson@intel.com> writes:
> > +#if IS_ENABLED(CONFIG_HYPERV)
> > enum ept_pointers_status ept_pointers_match;
> > spinlock_t ept_pointer_lock;
> > +#endif
>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> In case ept_pointers_match/ept_pointer_lock are useless for TDX we may
> want to find better names for them to make it clear this is a Hyper-V
> thingy (e.g. something like hv_tlb_ept_match/hv_tlb_ept_lock).
Good call. I'll send a v2, looking at hv_remote_flush_tlb_with_range(), I
think there are additional cleanups/optimizations that can be done, e.g. do the
extra flushes only on vCPUs with a mistmatching EPTP instead of flushing all
vCPUs' EPTPs if _any_ vCPU has a mismatched EPTP.
>
> > };
> >
> > bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
>
> --
> Vitaly
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-09-24 18:04 [PATCH] KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd() Sean Christopherson
2020-09-25 9:59 ` Vitaly Kuznetsov
2020-09-25 16:24 ` Sean Christopherson
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