x86/irq: Remove bitfields in posted interrupt descriptor

Mixture of bitfields and types is weird and really not intuitive, remove
bitfields and use typed data exclusively. Bitfields often result in
inferior machine code.

Suggested-by: Sean Christopherson <seanjc@google.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240423174114.526704-4-jacob.jun.pan@linux.intel.com
Link: https://lore.kernel.org/all/20240404101735.402feec8@jacob-builder/T/#mf66e34a82a48f4d8e2926b5581eff59a122de53a

diff --git a/arch/x86/include/asm/posted_intr.h b/arch/x86/include/asm/posted_intr.h
index acf237b2882ebaffa9c9ea032faf1e8bbd9700ba..20e31891de15f7bd55c69ec4cdd4320aee71648c 100644 (file)
--- a/arch/x86/include/asm/posted_intr.h
+++ b/arch/x86/include/asm/posted_intr.h
@@ -15,17 +15,9 @@ struct pi_desc {
        };
        union {
                struct {
-                               /* bit 256 - Outstanding Notification */
-                       u16     on      : 1,
-                               /* bit 257 - Suppress Notification */
-                               sn      : 1,
-                               /* bit 271:258 - Reserved */
-                               rsvd_1  : 14;
-                               /* bit 279:272 - Notification Vector */
+                       u16     notifications; /* Suppress and outstanding bits */
                        u8      nv;
-                               /* bit 287:280 - Reserved */
                        u8      rsvd_2;
-                               /* bit 319:288 - Notification Destination */
                        u32     ndst;
                };
                u64 control;
@@ -88,4 +80,15 @@ static inline bool pi_test_sn(struct pi_desc *pi_desc)
        return test_bit(POSTED_INTR_SN, (unsigned long *)&pi_desc->control);
 }
 
+/* Non-atomic helpers */
+static inline void __pi_set_sn(struct pi_desc *pi_desc)
+{
+       pi_desc->notifications |= BIT(POSTED_INTR_SN);
+}
+
+static inline void __pi_clear_sn(struct pi_desc *pi_desc)
+{
+       pi_desc->notifications &= ~BIT(POSTED_INTR_SN);
+}
+
 #endif /* _X86_POSTED_INTR_H */

diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index af662312fd07788ced21ec86a630280199de8e98..ec08fa3caf43ce465b562e756cf88eeba04c95b7 100644 (file)
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -107,7 +107,7 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
                 * handle task migration (@cpu != vcpu->cpu).
                 */
                new.ndst = dest;
-               new.sn = 0;
+               __pi_clear_sn(&new);
 
                /*
                 * Restore the notification vector; in the blocking case, the
@@ -157,7 +157,7 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu)
                      &per_cpu(wakeup_vcpus_on_cpu, vcpu->cpu));
        raw_spin_unlock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
 
-       WARN(pi_desc->sn, "PI descriptor SN field set before blocking");
+       WARN(pi_test_sn(pi_desc), "PI descriptor SN field set before blocking");
 
        old.control = READ_ONCE(pi_desc->control);
        do {

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 273d26492e41d6af939165baa7072aa361bf2498..becefaf95cabd1c5372c1cd4cf84913402d1db81 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4845,7 +4845,7 @@ static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)
         * or POSTED_INTR_WAKEUP_VECTOR.
         */
        vmx->pi_desc.nv = POSTED_INTR_VECTOR;
-       vmx->pi_desc.sn = 1;
+       __pi_set_sn(&vmx->pi_desc);
 }
 
 static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)