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From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>
Subject: [RFC PATCH v6 077/104] KVM: TDX: remove use of struct vcpu_vmx from posted_interrupt.c
Date:   Thu,  5 May 2022 11:15:11 -0700
Message-Id: <9e5418d1de1c924e3d99bd3b3705e59cf8945085.1651774250.git.isaku.yamahata@intel.com>
In-Reply-To: <cover.1651774250.git.isaku.yamahata@intel.com>
References: <cover.1651774250.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

As TDX will use posted_interrupt.c, the use of struct vcpu_vmx is a blocker.
Because the members of struct pi_desc pi_desc and struct list_head
pi_wakeup_list are only used in posted_interrupt.c, introduce common
structure, struct vcpu_pi, make vcpu_vmx and vcpu_tdx has same layout
in the top of structure.

To minimize the diff size, avoid code conversion like,
vmx->pi_desc => vmx->common->pi_desc.  Instead add compile time check
if the layout is expected.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 arch/x86/kvm/vmx/posted_intr.c | 41 ++++++++++++++++++++++++++--------
 arch/x86/kvm/vmx/posted_intr.h | 11 +++++++++
 arch/x86/kvm/vmx/tdx.c         |  1 +
 arch/x86/kvm/vmx/tdx.h         |  8 +++++++
 arch/x86/kvm/vmx/vmx.h         | 14 +++++++-----
 5 files changed, 60 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 160653925f38..0bc7a848b319 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -9,6 +9,7 @@
 #include "posted_intr.h"
 #include "trace.h"
 #include "vmx.h"
+#include "tdx.h"
 
 /*
  * Maintain a per-CPU list of vCPUs that need to be awakened by wakeup_handler()
@@ -29,9 +30,29 @@ static DEFINE_PER_CPU(struct list_head, wakeup_vcpus_on_cpu);
  */
 static DEFINE_PER_CPU(raw_spinlock_t, wakeup_vcpus_on_cpu_lock);
 
+/*
+ * The layout of the head of struct vcpu_vmx and struct vcpu_tdx must match with
+ * struct vcpu_pi.
+ */
+static_assert(offsetof(struct vcpu_pi, pi_desc) ==
+	      offsetof(struct vcpu_vmx, pi_desc));
+static_assert(offsetof(struct vcpu_pi, pi_wakeup_list) ==
+	      offsetof(struct vcpu_vmx, pi_wakeup_list));
+#ifdef CONFIG_INTEL_TDX_HOST
+static_assert(offsetof(struct vcpu_pi, pi_desc) ==
+	      offsetof(struct vcpu_tdx, pi_desc));
+static_assert(offsetof(struct vcpu_pi, pi_wakeup_list) ==
+	      offsetof(struct vcpu_tdx, pi_wakeup_list));
+#endif
+
+static inline struct vcpu_pi *vcpu_to_pi(struct kvm_vcpu *vcpu)
+{
+	return (struct vcpu_pi*)vcpu;
+}
+
 static inline struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
 {
-	return &(to_vmx(vcpu)->pi_desc);
+	return &vcpu_to_pi(vcpu)->pi_desc;
 }
 
 static int pi_try_set_control(struct pi_desc *pi_desc, u64 old, u64 new)
@@ -50,8 +71,8 @@ static int pi_try_set_control(struct pi_desc *pi_desc, u64 old, u64 new)
 
 void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
 {
-	struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
-	struct vcpu_vmx *vmx = to_vmx(vcpu);
+	struct vcpu_pi *vcpu_pi = vcpu_to_pi(vcpu);
+	struct pi_desc *pi_desc = &vcpu_pi->pi_desc;
 	struct pi_desc old, new;
 	unsigned long flags;
 	unsigned int dest;
@@ -88,7 +109,7 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
 	 */
 	if (pi_desc->nv == POSTED_INTR_WAKEUP_VECTOR) {
 		raw_spin_lock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
-		list_del(&vmx->pi_wakeup_list);
+		list_del(&vcpu_pi->pi_wakeup_list);
 		raw_spin_unlock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
 	}
 
@@ -142,15 +163,15 @@ static bool vmx_can_use_vtd_pi(struct kvm *kvm)
  */
 static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu)
 {
-	struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
-	struct vcpu_vmx *vmx = to_vmx(vcpu);
+	struct vcpu_pi *vcpu_pi = vcpu_to_pi(vcpu);
+	struct pi_desc *pi_desc = &vcpu_pi->pi_desc;
 	struct pi_desc old, new;
 	unsigned long flags;
 
 	local_irq_save(flags);
 
 	raw_spin_lock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
-	list_add_tail(&vmx->pi_wakeup_list,
+	list_add_tail(&vcpu_pi->pi_wakeup_list,
 		      &per_cpu(wakeup_vcpus_on_cpu, vcpu->cpu));
 	raw_spin_unlock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
 
@@ -187,7 +208,8 @@ static bool vmx_needs_pi_wakeup(struct kvm_vcpu *vcpu)
 	 * notification vector is switched to the one that calls
 	 * back to the pi_wakeup_handler() function.
 	 */
-	return vmx_can_use_ipiv(vcpu) || vmx_can_use_vtd_pi(vcpu->kvm);
+	return (vmx_can_use_ipiv(vcpu) && !is_td_vcpu(vcpu)) ||
+		vmx_can_use_vtd_pi(vcpu->kvm);
 }
 
 void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
@@ -197,7 +219,8 @@ void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
 	if (!vmx_needs_pi_wakeup(vcpu))
 		return;
 
-	if (kvm_vcpu_is_blocking(vcpu) && !vmx_interrupt_blocked(vcpu))
+	if (kvm_vcpu_is_blocking(vcpu) &&
+	    (is_td_vcpu(vcpu) || !vmx_interrupt_blocked(vcpu)))
 		pi_enable_wakeup_handler(vcpu);
 
 	/*
diff --git a/arch/x86/kvm/vmx/posted_intr.h b/arch/x86/kvm/vmx/posted_intr.h
index 26992076552e..2fe8222308b2 100644
--- a/arch/x86/kvm/vmx/posted_intr.h
+++ b/arch/x86/kvm/vmx/posted_intr.h
@@ -94,6 +94,17 @@ static inline bool pi_test_sn(struct pi_desc *pi_desc)
 			(unsigned long *)&pi_desc->control);
 }
 
+struct vcpu_pi {
+	struct kvm_vcpu	vcpu;
+
+	/* Posted interrupt descriptor */
+	struct pi_desc pi_desc;
+
+	/* Used if this vCPU is waiting for PI notification wakeup. */
+	struct list_head pi_wakeup_list;
+	/* Until here common layout betwwn vcpu_vmx and vcpu_tdx. */
+};
+
 void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu);
 void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu);
 void pi_wakeup_handler(void);
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 98e0a907dc68..758af6ec3507 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -526,6 +526,7 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu)
 		return -EINVAL;
 
 	vcpu->arch.apic->guest_apic_protected = true;
+	INIT_LIST_HEAD(&tdx->pi_wakeup_list);
 
 	ret = tdx_alloc_td_page(&tdx->tdvpr);
 	if (ret)
diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index 32e05efa70f9..1268a49fdf18 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -4,6 +4,7 @@
 
 #ifdef CONFIG_INTEL_TDX_HOST
 
+#include "posted_intr.h"
 #include "pmu_intel.h"
 #include "tdx_ops.h"
 
@@ -82,6 +83,13 @@ union tdx_exit_reason {
 struct vcpu_tdx {
 	struct kvm_vcpu	vcpu;
 
+	/* Posted interrupt descriptor */
+	struct pi_desc pi_desc;
+
+	/* Used if this vCPU is waiting for PI notification wakeup. */
+	struct list_head pi_wakeup_list;
+	/* Until here same layout to struct vcpu_pi. */
+
 	struct tdx_td_page tdvpr;
 	struct tdx_td_page *tdvpx;
 
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index f49be71290bd..4b2e610df657 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -224,6 +224,14 @@ struct nested_vmx {
 
 struct vcpu_vmx {
 	struct kvm_vcpu       vcpu;
+
+	/* Posted interrupt descriptor */
+	struct pi_desc pi_desc;
+
+	/* Used if this vCPU is waiting for PI notification wakeup. */
+	struct list_head pi_wakeup_list;
+	/* Until here same layout to struct vcpu_pi. */
+
 	u8                    fail;
 	u8		      x2apic_msr_bitmap_mode;
 
@@ -293,12 +301,6 @@ struct vcpu_vmx {
 
 	union vmx_exit_reason exit_reason;
 
-	/* Posted interrupt descriptor */
-	struct pi_desc pi_desc;
-
-	/* Used if this vCPU is waiting for PI notification wakeup. */
-	struct list_head pi_wakeup_list;
-
 	/* Support for a guest hypervisor (nested VMX) */
 	struct nested_vmx nested;
 
-- 
2.25.1