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Message-ID: <20231025152406.1879274-3-vkuznets@redhat.com>
Date: Wed, 25 Oct 2023 17:23:54 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>,
Maxim Levitsky <mlevitsk@...hat.com>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 02/14] KVM: x86: hyper-v: Move Hyper-V partition assist page out of Hyper-V emulation context
Hyper-V partition assist page is used when KVM runs on top of Hyper-V and
is not used for Windows/Hyper-V guests on KVM, this means that 'hv_pa_pg'
placement in 'struct kvm_hv' is unfortunate. As a preparation to making
Hyper-V emulation optional, move 'hv_pa_pg' to 'struct kvm_arch' and put it
under CONFIG_HYPERV.
While on it, introduce hv_get_partition_assist_page() helper to allocate
partition assist page. Move the comment explaining why we use a single page
for all vCPUs from VMX and expand it a bit.
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/kvm_onhyperv.h | 20 ++++++++++++++++++++
arch/x86/kvm/svm/svm_onhyperv.c | 10 +++-------
arch/x86/kvm/vmx/vmx.c | 14 +++-----------
arch/x86/kvm/x86.c | 4 +++-
5 files changed, 30 insertions(+), 20 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d107516b4591..7fb2810f4573 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1125,7 +1125,6 @@ struct kvm_hv {
*/
unsigned int synic_auto_eoi_used;
- struct hv_partition_assist_pg *hv_pa_pg;
struct kvm_hv_syndbg hv_syndbg;
};
@@ -1447,6 +1446,7 @@ struct kvm_arch {
#if IS_ENABLED(CONFIG_HYPERV)
hpa_t hv_root_tdp;
spinlock_t hv_root_tdp_lock;
+ struct hv_partition_assist_pg *hv_pa_pg;
#endif
/*
* VM-scope maximum vCPU ID. Used to determine the size of structures
diff --git a/arch/x86/kvm/kvm_onhyperv.h b/arch/x86/kvm/kvm_onhyperv.h
index f9ca3e7432b2..eefab3dc8498 100644
--- a/arch/x86/kvm/kvm_onhyperv.h
+++ b/arch/x86/kvm/kvm_onhyperv.h
@@ -10,6 +10,26 @@
int hv_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, gfn_t nr_pages);
int hv_flush_remote_tlbs(struct kvm *kvm);
void hv_track_root_tdp(struct kvm_vcpu *vcpu, hpa_t root_tdp);
+static inline hpa_t hv_get_partition_assist_page(struct kvm_vcpu *vcpu)
+{
+ /*
+ * Partition assist page is something which Hyper-V running in L0
+ * requires from KVM running in L1 before direct TLB flush for L2
+ * guests can be enabled. KVM doesn't currently use the page but to
+ * comply with TLFS it still needs to be allocated. For now, this
+ * is a single page shared among all vCPUs.
+ */
+ struct hv_partition_assist_pg **p_hv_pa_pg =
+ &vcpu->kvm->arch.hv_pa_pg;
+
+ if (!*p_hv_pa_pg)
+ *p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL_ACCOUNT);
+
+ if (!*p_hv_pa_pg)
+ return INVALID_PAGE;
+
+ return __pa(*p_hv_pa_pg);
+}
#else /* !CONFIG_HYPERV */
static inline int hv_flush_remote_tlbs(struct kvm *kvm)
{
diff --git a/arch/x86/kvm/svm/svm_onhyperv.c b/arch/x86/kvm/svm/svm_onhyperv.c
index 7af8422d3382..3971b3ea5d04 100644
--- a/arch/x86/kvm/svm/svm_onhyperv.c
+++ b/arch/x86/kvm/svm/svm_onhyperv.c
@@ -18,18 +18,14 @@
int svm_hv_enable_l2_tlb_flush(struct kvm_vcpu *vcpu)
{
struct hv_vmcb_enlightenments *hve;
- struct hv_partition_assist_pg **p_hv_pa_pg =
- &to_kvm_hv(vcpu->kvm)->hv_pa_pg;
+ hpa_t partition_assist_page = hv_get_partition_assist_page(vcpu);
- if (!*p_hv_pa_pg)
- *p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL);
-
- if (!*p_hv_pa_pg)
+ if (partition_assist_page == INVALID_PAGE)
return -ENOMEM;
hve = &to_svm(vcpu)->vmcb->control.hv_enlightenments;
- hve->partition_assist_page = __pa(*p_hv_pa_pg);
+ hve->partition_assist_page = partition_assist_page;
hve->hv_vm_id = (unsigned long)vcpu->kvm;
if (!hve->hv_enlightenments_control.nested_flush_hypercall) {
hve->hv_enlightenments_control.nested_flush_hypercall = 1;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index be20a60047b1..cb4591405f14 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -523,22 +523,14 @@ module_param(enlightened_vmcs, bool, 0444);
static int hv_enable_l2_tlb_flush(struct kvm_vcpu *vcpu)
{
struct hv_enlightened_vmcs *evmcs;
- struct hv_partition_assist_pg **p_hv_pa_pg =
- &to_kvm_hv(vcpu->kvm)->hv_pa_pg;
- /*
- * Synthetic VM-Exit is not enabled in current code and so All
- * evmcs in singe VM shares same assist page.
- */
- if (!*p_hv_pa_pg)
- *p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL_ACCOUNT);
+ hpa_t partition_assist_page = hv_get_partition_assist_page(vcpu);
- if (!*p_hv_pa_pg)
+ if (partition_assist_page == INVALID_PAGE)
return -ENOMEM;
evmcs = (struct hv_enlightened_vmcs *)to_vmx(vcpu)->loaded_vmcs->vmcs;
- evmcs->partition_assist_page =
- __pa(*p_hv_pa_pg);
+ evmcs->partition_assist_page = partition_assist_page;
evmcs->hv_vm_id = (unsigned long)vcpu->kvm;
evmcs->hv_enlightenments_control.nested_flush_hypercall = 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d632931fa545..cc2524598368 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12425,7 +12425,9 @@ void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu)
void kvm_arch_free_vm(struct kvm *kvm)
{
- kfree(to_kvm_hv(kvm)->hv_pa_pg);
+#if IS_ENABLED(CONFIG_HYPERV)
+ kfree(kvm->arch.hv_pa_pg);
+#endif
__kvm_arch_free_vm(kvm);
}
--
2.41.0
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