From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: LKML <linux-kernel@vger.kernel.org>, X86 Kernel <x86@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
iommu@lists.linux.dev, Thomas Gleixner <tglx@linutronix.de>,
"Lu Baolu" <baolu.lu@linux.intel.com>,
kvm@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>,
Joerg Roedel <joro@8bytes.org>, "H. Peter Anvin" <hpa@zytor.com>,
"Borislav Petkov" <bp@alien8.de>,
"Ingo Molnar" <mingo@redhat.com>
Cc: Paul Luse <paul.e.luse@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Jens Axboe <axboe@kernel.dk>, Raj Ashok <ashok.raj@intel.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
maz@kernel.org, seanjc@google.com,
"Robin Murphy" <robin.murphy@arm.com>,
jim.harris@samsung.com, a.manzanares@samsung.com,
"Bjorn Helgaas" <helgaas@kernel.org>,
guang.zeng@intel.com, robert.hoo.linux@gmail.com,
oliver.sang@intel.com, acme@kernel.org,
Jacob Pan <jacob.jun.pan@linux.intel.com>
Subject: [PATCH v3 03/12] x86/irq: Remove bitfields in posted interrupt descriptor
Date: Tue, 23 Apr 2024 10:41:05 -0700 [thread overview]
Message-ID: <20240423174114.526704-4-jacob.jun.pan@linux.intel.com> (raw)
In-Reply-To: <20240423174114.526704-1-jacob.jun.pan@linux.intel.com>
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.
Link: https://lore.kernel.org/all/20240404101735.402feec8@jacob-builder/T/#mf66e34a82a48f4d8e2926b5581eff59a122de53a
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>
---
v3:
- Fix a bug where SN bit position was used as the mask, reported by
Oliver Sang.
- Add and use non-atomic helpers to manipulate SN bit
- Use pi_test_sn() instead of open coding
v2:
- Replace bitfields, no more mix.
---
arch/x86/include/asm/posted_intr.h | 21 ++++++++++++---------
arch/x86/kvm/vmx/posted_intr.c | 4 ++--
arch/x86/kvm/vmx/vmx.c | 2 +-
3 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/posted_intr.h b/arch/x86/include/asm/posted_intr.h
index acf237b2882e..20e31891de15 100644
--- 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 af662312fd07..ec08fa3caf43 100644
--- 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 d94bb069bac9..f505745913c8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4843,7 +4843,7 @@ 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)
--
2.25.1
next prev parent reply other threads:[~2024-04-23 17:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-23 17:41 [PATCH v3 00/12] Coalesced Interrupt Delivery with posted MSI Jacob Pan
2024-04-23 17:41 ` [PATCH v3 01/12] KVM: VMX: Move posted interrupt descriptor out of vmx code Jacob Pan
2024-04-23 17:41 ` [PATCH v3 02/12] x86/irq: Unionize PID.PIR for 64bit access w/o casting Jacob Pan
2024-04-23 17:41 ` Jacob Pan [this message]
2024-05-01 7:29 ` [PATCH v3 03/12] x86/irq: Remove bitfields in posted interrupt descriptor Oliver Sang
2024-04-23 17:41 ` [PATCH v3 04/12] x86/irq: Add a Kconfig option for posted MSI Jacob Pan
2024-04-23 17:41 ` [PATCH v3 05/12] x86/irq: Reserve a per CPU IDT vector for posted MSIs Jacob Pan
2024-04-23 17:41 ` [PATCH v3 06/12] x86/irq: Set up per host CPU posted interrupt descriptors Jacob Pan
2024-04-23 17:41 ` [PATCH v3 07/12] x86/irq: Factor out calling ISR from common_interrupt Jacob Pan
2024-04-23 17:41 ` [PATCH v3 08/12] x86/irq: Install posted MSI notification handler Jacob Pan
2024-04-23 17:41 ` [PATCH v3 09/12] x86/irq: Factor out common code for checking pending interrupts Jacob Pan
2024-04-23 17:41 ` [PATCH v3 10/12] x86/irq: Extend checks for pending vectors to posted interrupts Jacob Pan
2024-04-23 17:41 ` [PATCH v3 11/12] iommu/vt-d: Make posted MSI an opt-in cmdline option Jacob Pan
2024-04-23 17:41 ` [PATCH v3 12/12] iommu/vt-d: Enable posted mode for device MSIs Jacob Pan
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