On Mon, Feb 03, 2020 at 09:41:18AM +0000, Andrew Murray wrote:

On Mon, Feb 03, 2020 at 01:03:12PM +0800, Boqun Feng wrote:

quoted

Currently, retarget_msi_interrupt and other structures it relys on are
defined in pci-hyperv.c. However, those structures are actually defined
in Hypervisor Top-Level Functional Specification [1] and may be
different in sizes of fields or layout from architecture to
architecture. Therefore, this patch moves those definitions into x86's

Nit: Rather than 'Therefore, this patch moves ...' - how about 'Let's move
...'?

quoted

tlfs header file to support virtual PCI on non-x86 architectures in the
future.

Besides, while I'm at it, rename retarget_msi_interrupt to

Nit: 'Besides, while I'm at it' - this type of wording describes what
*you've* done rather than what the patch is doing. You could replace
that quoted text with 'Additionally, '

quoted

hv_retarget_msi_interrupt for the consistent name convention, also

Nit: s/name/naming

Thanks for the suggestion on wording ;-)

quoted

mirroring the name in TLFS.

[1]: https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs

Signed-off-by: Boqun Feng (Microsoft) <redacted>
---
 arch/x86/include/asm/hyperv-tlfs.h  | 31 ++++++++++++++++++++++++++
 drivers/pci/controller/pci-hyperv.c | 34 ++---------------------------
 2 files changed, 33 insertions(+), 32 deletions(-)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 739bd89226a5..4a76e442481a 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h

@@ -911,4 +911,35 @@ struct hv_tlb_flush_ex {
 struct hv_partition_assist_pg {
 	u32 tlb_lock_count;
 };
+
+struct hv_interrupt_entry {
+	u32 source;			/* 1 for MSI(-X) */
+	u32 reserved1;
+	u32 address;
+	u32 data;
+} __packed;

Why have you added __packed here? There is no mention of this change in the
commit log? Is it needed?

I'm simply following the convention of hyperv-tlfs.h: most of the
structures have this "__packed" attribute. I personally don't think this
attribute is necessary, but I was afraid that I was missing something
subtle. So a question for folks working on Hyper-V: why we need this
attribute on TLFS-defined structures? Most of those will have no
difference with or without this attribute, IIUC.

quoted

+
+/*
+ * flags for hv_device_interrupt_target.flags
+ */
+#define HV_DEVICE_INTERRUPT_TARGET_MULTICAST		1
+#define HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET	2
+
+struct hv_device_interrupt_target {
+	u32 vector;
+	u32 flags;
+	union {
+		u64 vp_mask;
+		struct hv_vpset vp_set;
+	};
+} __packed;

Same here.

quoted

+
+/* HvRetargetDeviceInterrupt hypercall */
+struct hv_retarget_device_interrupt {
+	u64 partition_id;

Why drop the 'self' comment?

Good catch, TLFS does say this field must be 'self'. I will add it in
next version.

quoted

+	u64 device_id;
+	struct hv_interrupt_entry int_entry;
+	u64 reserved2;
+	struct hv_device_interrupt_target int_target;
+} __packed __aligned(8);
 #endif

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index aacfcc90d929..0d9b74503577 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c

@@ -406,36 +406,6 @@ struct pci_eject_response {
 
 static int pci_ring_size = (4 * PAGE_SIZE);
 
-struct hv_interrupt_entry {
-	u32	source;			/* 1 for MSI(-X) */
-	u32	reserved1;
-	u32	address;
-	u32	data;
-};
-
-/*
- * flags for hv_device_interrupt_target.flags
- */
-#define HV_DEVICE_INTERRUPT_TARGET_MULTICAST		1
-#define HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET	2
-
-struct hv_device_interrupt_target {
-	u32	vector;
-	u32	flags;
-	union {
-		u64		 vp_mask;
-		struct hv_vpset vp_set;
-	};
-};
-
-struct retarget_msi_interrupt {
-	u64	partition_id;		/* use "self" */
-	u64	device_id;
-	struct hv_interrupt_entry int_entry;
-	u64	reserved2;
-	struct hv_device_interrupt_target int_target;
-} __packed __aligned(8);
-
 /*
  * Driver specific state.
  */

@@ -482,7 +452,7 @@ struct hv_pcibus_device {
 	struct workqueue_struct *wq;
 
 	/* hypercall arg, must not cross page boundary */
-	struct retarget_msi_interrupt retarget_msi_interrupt_params;
+	struct hv_retarget_device_interrupt retarget_msi_interrupt_params;
 
 	/*
 	 * Don't put anything here: retarget_msi_interrupt_params must be last

@@ -1178,7 +1148,7 @@ static void hv_irq_unmask(struct irq_data *data)
 {
 	struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
 	struct irq_cfg *cfg = irqd_cfg(data);
-	struct retarget_msi_interrupt *params;
+	struct hv_retarget_device_interrupt *params;

pci-hyperv.c also makes use of retarget_msi_interrupt_lock - it's really clear
from this name what it protects, however your rename now makes this more
confusing.

Likewise there is a comment in hv_pci_probe that refers to
retarget_msi_interrupt_params which is now stale.

But 'retarget_msi_interrupt_params' is the name of field in
hv_pcibus_device, so is 'retarget_msi_interrupt_lock'. And what I change
is the name of type. I believe people can tell the relationship from
the name of the fields, and the comment of hv_pci_probe actually refers
to the field rather than the type.

It may be helpful to rename hv_retarget_device_interrupt for consistency with
the docs - however please make sure you catch all the references - I'd suggest
that the move and the rename are in different patches.

If the renaming requires a lot of work (e.g. need to change multiple
references), I will follow your suggestion. But seems it's not the case
for this renaming.

Regards,
Boqun

Thanks,

Andrew Murray

quoted

 	struct hv_pcibus_device *hbus;
 	struct cpumask *dest;
 	cpumask_var_t tmp;
-- 
2.24.1