Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1374198 > unrolled thread

[PART2 RFC v1 5/9] iommu/amd: Introduce amd_iommu_update_ga()

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PART2 RFC v1 5/9] iommu/amd: Introduce amd_iommu_update_ga() Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> - 2016-04-08 15:00 +0200
    Re: [PART2 RFC v1 5/9] iommu/amd: Introduce amd_iommu_update_ga() Radim Krčmář <rkrcmar@redhat.com> - 2016-04-13 19:10 +0200

#1374198 — [PART2 RFC v1 5/9] iommu/amd: Introduce amd_iommu_update_ga()

From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

This patch introduces a new IOMMU interface, amd_iommu_update_ga(),
which allows KVM (SVM) to update existing posted interrupt IOMMU IRTE when
load/unload vcpu.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd_iommu.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/amd-iommu.h |  8 ++++++
 2 files changed, 78 insertions(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 8cdde339..1d17597 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -4330,4 +4330,74 @@ int amd_iommu_create_irq_domain(struct amd_iommu *iommu)
 
 	return 0;
 }
+
+static int
+set_irte_ga(struct amd_iommu *iommu, unsigned int devid,
+	    u64 base, int cpu, bool is_run)
+{
+	struct irq_remap_table *irt = get_irq_table(devid, false);
+	unsigned long flags;
+	int index;
+
+	if (!irt)
+		return -ENODEV;
+
+	spin_lock_irqsave(&irt->lock, flags);
+
+	for (index = irt->min_index; index < MAX_IRQS_PER_TABLE; ++index) {
+		struct irte_ga *irte = amd_iommu_get_irte(irt, index);
+
+		if (!irte->lo.fields_vapic.guest_mode)
+			continue;
+
+		irte->hi.fields.ga_root_ptr = (base >> 12);
+		irte->lo.fields_vapic.destination = cpu;
+		irte->lo.fields_vapic.is_run = is_run;
+		barrier();
+	}
+
+	spin_unlock_irqrestore(&irt->lock, flags);
+
+	iommu_flush_irt(iommu, devid);
+	iommu_completion_wait(iommu);
+
+	return 0;
+}
+
+int amd_iommu_update_ga(u32 vcpu_id, u32 cpu, u32 ga_tag,
+			u64 base, bool is_run)
+{
+	unsigned long flags;
+	struct amd_iommu *iommu;
+
+	if (amd_iommu_guest_ir < AMD_IOMMU_GUEST_IR_GA)
+		return 0;
+
+	for_each_iommu(iommu) {
+		struct amd_ir_data *ir_data;
+
+		spin_lock_irqsave(&iommu->ga_hash_lock, flags);
+
+		hash_for_each_possible(iommu->ga_hash, ir_data, hnode,
+				       AMD_IOMMU_GATAG(ga_tag, vcpu_id)) {
+			struct iommu_dev_data *dev_data;
+
+			if (!ir_data)
+				break;
+
+			dev_data = search_dev_data(ir_data->irq_2_irte.devid);
+
+			if (!dev_data || !dev_data->guest_mode)
+				continue;
+
+			set_irte_ga(iommu, ir_data->irq_2_irte.devid,
+				    base, cpu, is_run);
+		}
+
+		spin_unlock_irqrestore(&iommu->ga_hash_lock, flags);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(amd_iommu_update_ga);
 #endif
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index 36648fe..e52cee5 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -173,6 +173,9 @@ extern int amd_iommu_set_invalidate_ctx_cb(struct pci_dev *pdev,
 extern int
 amd_iommu_register_ga_log_notifier(int (*notifier)(int, int, int));
 
+extern int
+amd_iommu_update_ga(u32 vcpu_id, u32 cpu, u32 ga_tag, u64 base, bool is_run);
+
 #else
 
 static inline int amd_iommu_detect(void) { return -ENODEV; }
@@ -183,6 +186,11 @@ amd_iommu_register_ga_log_notifier(int (*notifier)(int, int, int))
 	return 0;
 }
 
+static inline int
+amd_iommu_update_ga(u32 vcpu_id, u32 cpu, u32 ga_tag, u64 base, bool is_run)
+{
+	return 0;
+}
 #endif
 
 #endif /* _ASM_X86_AMD_IOMMU_H */
-- 
1.9.1

[toc] | [next] | [standalone]

#1378105

2016-04-08 07:49-0500, Suravee Suthikulpanit:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> 
> This patch introduces a new IOMMU interface, amd_iommu_update_ga(),
> which allows KVM (SVM) to update existing posted interrupt IOMMU IRTE when
> load/unload vcpu.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> @@ -4330,4 +4330,74 @@ int amd_iommu_create_irq_domain(struct amd_iommu *iommu)
> +int amd_iommu_update_ga(u32 vcpu_id, u32 cpu, u32 ga_tag,

It'd be nicer to generate the tag on SVM side and pass it whole -- IOMMU
doesn't have to care how hypervisors use the tag.

> +			u64 base, bool is_run)
> +{
> +	unsigned long flags;
> +	struct amd_iommu *iommu;
> +
> +	if (amd_iommu_guest_ir < AMD_IOMMU_GUEST_IR_GA)
> +		return 0;
> +
> +	for_each_iommu(iommu) {
> +		struct amd_ir_data *ir_data;
> +
> +		spin_lock_irqsave(&iommu->ga_hash_lock, flags);
> +
> +		hash_for_each_possible(iommu->ga_hash, ir_data, hnode,
> +				       AMD_IOMMU_GATAG(ga_tag, vcpu_id)) {

All tags can map into the same bucket.  Code below doesn't check that
the ir_data belongs to the tag and will modify unrelated IRTEs.

Have you considered a per-VCPU list of IRTEs on the SVM side?

> +			struct iommu_dev_data *dev_data;
> +			if (!ir_data)

(ir_data can't be NULL.)

> +				break;
> +
> +			dev_data = search_dev_data(ir_data->irq_2_irte.devid);
> +
> +			if (!dev_data || !dev_data->guest_mode)
> +				continue;

(guest_mode can be also read from the irte.)

> +			set_irte_ga(iommu, ir_data->irq_2_irte.devid,
> +				    base, cpu, is_run);

set_irte_ga() is pretty expensive -- do we need to invalidate the irt
when changing cpu and is_run?

2.2.5.2 Interrupt Virtualization Tables with Guest Virtual APIC Enabled,
point 9, bullet 5 says that IRTE is read from memory before considering
IsRun, GATag and Destination, which makes me think that avoiding races
can be faster in the common case.

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web