On Wed, 2022-05-18 at 14:43 +0200, Vitaly Kuznetsov wrote:

Maxim Levitsky [off-list ref] writes:

quoted

On Thu, 2022-04-14 at 15:19 +0200, Vitaly Kuznetsov wrote:

quoted

Hyper-V supports injecting synthetic L2->L1 exit after performing
L2 TLB flush operation but the procedure is vendor specific.
Introduce .post_hv_l2_tlb_flush() nested hook for it.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/Makefile           |  3 ++-
 arch/x86/kvm/svm/hyperv.c       | 11 +++++++++++
 arch/x86/kvm/svm/hyperv.h       |  2 ++
 arch/x86/kvm/svm/nested.c       |  1 +
 arch/x86/kvm/vmx/evmcs.c        |  4 ++++
 arch/x86/kvm/vmx/evmcs.h        |  1 +
 arch/x86/kvm/vmx/nested.c       |  1 +
 8 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/kvm/svm/hyperv.c

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8b2a52bf26c0..ce62fde5f4ff 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h

@@ -1558,6 +1558,7 @@ struct kvm_x86_nested_ops {
 	int (*enable_evmcs)(struct kvm_vcpu *vcpu,
 			    uint16_t *vmcs_version);
 	uint16_t (*get_evmcs_version)(struct kvm_vcpu *vcpu);
+	void (*post_hv_l2_tlb_flush)(struct kvm_vcpu *vcpu);
 };
 
 struct kvm_x86_init_ops {

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 30f244b64523..b6d53b045692 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile

@@ -25,7 +25,8 @@ kvm-intel-y		+= vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \
 			   vmx/evmcs.o vmx/nested.o vmx/posted_intr.o
 kvm-intel-$(CONFIG_X86_SGX_KVM)	+= vmx/sgx.o
 
-kvm-amd-y		+= svm/svm.o svm/vmenter.o svm/pmu.o svm/nested.o svm/avic.o svm/sev.o
+kvm-amd-y		+= svm/svm.o svm/vmenter.o svm/pmu.o svm/nested.o svm/avic.o \
+			   svm/sev.o svm/hyperv.o
 
 ifdef CONFIG_HYPERV
 kvm-amd-y		+= svm/svm_onhyperv.o

diff --git a/arch/x86/kvm/svm/hyperv.c b/arch/x86/kvm/svm/hyperv.c
new file mode 100644
index 000000000000..c0749fc282fe
--- /dev/null
+++ b/arch/x86/kvm/svm/hyperv.c

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD SVM specific code for Hyper-V on KVM.
+ *
+ * Copyright 2022 Red Hat, Inc. and/or its affiliates.
+ */
+#include "hyperv.h"
+
+void svm_post_hv_l2_tlb_flush(struct kvm_vcpu *vcpu)
+{
+}

diff --git a/arch/x86/kvm/svm/hyperv.h b/arch/x86/kvm/svm/hyperv.h
index 8cf702fed7e5..a2b0d7580b0d 100644
--- a/arch/x86/kvm/svm/hyperv.h
+++ b/arch/x86/kvm/svm/hyperv.h

@@ -48,4 +48,6 @@ static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu)
 	hv_vcpu->nested.vp_id = hve->hv_vp_id;
 }
 
+void svm_post_hv_l2_tlb_flush(struct kvm_vcpu *vcpu);
+
 #endif /* __ARCH_X86_KVM_SVM_HYPERV_H__ */

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 2d1a76343404..de3f27301b5c 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c

@@ -1665,4 +1665,5 @@ struct kvm_x86_nested_ops svm_nested_ops = {
 	.get_nested_state_pages = svm_get_nested_state_pages,
 	.get_state = svm_get_nested_state,
 	.set_state = svm_set_nested_state,
+	.post_hv_l2_tlb_flush = svm_post_hv_l2_tlb_flush,
 };

diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
index 87e3dc10edf4..e390e67496df 100644
--- a/arch/x86/kvm/vmx/evmcs.c
+++ b/arch/x86/kvm/vmx/evmcs.c

@@ -437,3 +437,7 @@ int nested_enable_evmcs(struct kvm_vcpu *vcpu,
 
 	return 0;
 }
+
+void vmx_post_hv_l2_tlb_flush(struct kvm_vcpu *vcpu)
+{
+}

diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
index 8d70f9aea94b..b120b0ead4f3 100644
--- a/arch/x86/kvm/vmx/evmcs.h
+++ b/arch/x86/kvm/vmx/evmcs.h

@@ -244,5 +244,6 @@ int nested_enable_evmcs(struct kvm_vcpu *vcpu,
 			uint16_t *vmcs_version);
 void nested_evmcs_filter_control_msr(u32 msr_index, u64 *pdata);
 int nested_evmcs_check_controls(struct vmcs12 *vmcs12);
+void vmx_post_hv_l2_tlb_flush(struct kvm_vcpu *vcpu);
 
 #endif /* __KVM_X86_VMX_EVMCS_H */

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index ee88921c6156..cc6c944b5815 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c

@@ -6850,4 +6850,5 @@ struct kvm_x86_nested_ops vmx_nested_ops = {
 	.write_log_dirty = nested_vmx_write_pml_buffer,
 	.enable_evmcs = nested_enable_evmcs,
 	.get_evmcs_version = nested_get_evmcs_version,
+	.post_hv_l2_tlb_flush = vmx_post_hv_l2_tlb_flush,
 };

I think that the name of the function is misleading, since it is not called
after each L2 HV tlb flush, but only after a flush which needs to inject
that synthetic VM exit.

I think something like 'inject_synthetic_l2_hv_tlb_flush_vmexit' 
(not a good name IMHO, but you get the idea) would be better.

Naming is hard indeed,

Indeed :-)

https://www.monkeyuser.com/2019/_/

hv_inject_synthetic_vmexit_post_tlb_flush()

Looks great!

Best regards,
	Maxim Levitsky

seems to be accurate.