diff mbox series

[V4,11/13] hyperv/IOMMU: Enable swiotlb bounce buffer for Isolation VM

Message ID 20210827172114.414281-12-ltykernel@gmail.com (mailing list archive)
State Not Applicable
Headers show
Series x86/Hyper-V: Add Hyper-V Isolation VM support | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Tianyu Lan Aug. 27, 2021, 5:21 p.m. UTC 
From: Tianyu Lan <Tianyu.Lan@microsoft.com>

hyperv Isolation VM requires bounce buffer support to copy
data from/to encrypted memory and so enable swiotlb force
mode to use swiotlb bounce buffer for DMA transaction.

In Isolation VM with AMD SEV, the bounce buffer needs to be
accessed via extra address space which is above shared_gpa_boundary
(E.G 39 bit address line) reported by Hyper-V CPUID ISOLATION_CONFIG.
The access physical address will be original physical address +
shared_gpa_boundary. The shared_gpa_boundary in the AMD SEV SNP
spec is called virtual top of memory(vTOM). Memory addresses below
vTOM are automatically treated as private while memory above
vTOM is treated as shared.

Swiotlb bounce buffer code calls dma_map_decrypted()
to mark bounce buffer visible to host and map it in extra
address space. Populate dma memory decrypted ops with hv
map/unmap function.

Hyper-V initalizes swiotlb bounce buffer and default swiotlb
needs to be disabled. pci_swiotlb_detect_override() and
pci_swiotlb_detect_4gb() enable the default one. To override
the setting, hyperv_swiotlb_detect() needs to run before
these detect functions which depends on the pci_xen_swiotlb_
init(). Make pci_xen_swiotlb_init() depends on the hyperv_swiotlb
_detect() to keep the order.

The map function vmap_pfn() can't work in the early place
hyperv_iommu_swiotlb_init() and so initialize swiotlb bounce
buffer in the hyperv_iommu_swiotlb_later_init().

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
Change since v3:
       * Get hyperv bounce bufffer size via default swiotlb
       bounce buffer size function and keep default size as
       same as the one in the AMD SEV VM.
---
 arch/x86/hyperv/ivm.c           | 28 +++++++++++++++
 arch/x86/include/asm/mshyperv.h |  2 ++
 arch/x86/mm/mem_encrypt.c       |  3 +-
 arch/x86/xen/pci-swiotlb-xen.c  |  3 +-
 drivers/hv/vmbus_drv.c          |  3 ++
 drivers/iommu/hyperv-iommu.c    | 61 +++++++++++++++++++++++++++++++++
 include/linux/hyperv.h          |  1 +
 7 files changed, 99 insertions(+), 2 deletions(-)

Comments

Michael Kelley (LINUX) Sept. 2, 2021, 1:27 a.m. UTC | #1 
From: Tianyu Lan <ltykernel@gmail.com> Sent: Friday, August 27, 2021 10:21 AM
> 
> hyperv Isolation VM requires bounce buffer support to copy
> data from/to encrypted memory and so enable swiotlb force
> mode to use swiotlb bounce buffer for DMA transaction.
> 
> In Isolation VM with AMD SEV, the bounce buffer needs to be
> accessed via extra address space which is above shared_gpa_boundary
> (E.G 39 bit address line) reported by Hyper-V CPUID ISOLATION_CONFIG.
> The access physical address will be original physical address +
> shared_gpa_boundary. The shared_gpa_boundary in the AMD SEV SNP
> spec is called virtual top of memory(vTOM). Memory addresses below
> vTOM are automatically treated as private while memory above
> vTOM is treated as shared.
> 
> Swiotlb bounce buffer code calls dma_map_decrypted()
> to mark bounce buffer visible to host and map it in extra
> address space. Populate dma memory decrypted ops with hv
> map/unmap function.
> 
> Hyper-V initalizes swiotlb bounce buffer and default swiotlb
> needs to be disabled. pci_swiotlb_detect_override() and
> pci_swiotlb_detect_4gb() enable the default one. To override
> the setting, hyperv_swiotlb_detect() needs to run before
> these detect functions which depends on the pci_xen_swiotlb_
> init(). Make pci_xen_swiotlb_init() depends on the hyperv_swiotlb
> _detect() to keep the order.
> 
> The map function vmap_pfn() can't work in the early place
> hyperv_iommu_swiotlb_init() and so initialize swiotlb bounce
> buffer in the hyperv_iommu_swiotlb_later_init().
> 
> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
> ---
> Change since v3:
>        * Get hyperv bounce bufffer size via default swiotlb
>        bounce buffer size function and keep default size as
>        same as the one in the AMD SEV VM.
> ---
>  arch/x86/hyperv/ivm.c           | 28 +++++++++++++++
>  arch/x86/include/asm/mshyperv.h |  2 ++
>  arch/x86/mm/mem_encrypt.c       |  3 +-
>  arch/x86/xen/pci-swiotlb-xen.c  |  3 +-
>  drivers/hv/vmbus_drv.c          |  3 ++
>  drivers/iommu/hyperv-iommu.c    | 61 +++++++++++++++++++++++++++++++++
>  include/linux/hyperv.h          |  1 +
>  7 files changed, 99 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index e761c67e2218..84563b3c9f3a 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -294,3 +294,31 @@ int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible)
> 
>  	return __hv_set_mem_host_visibility((void *)addr, numpages, visibility);
>  }
> +
> +/*
> + * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
> + */
> +void *hv_map_memory(void *addr, unsigned long size)
> +{
> +	unsigned long *pfns = kcalloc(size / HV_HYP_PAGE_SIZE,
> +				      sizeof(unsigned long), GFP_KERNEL);

Should be PAGE_SIZE, not HV_HYP_PAGE_SIZE, since this code
only manipulates guest page tables.  There's no communication with
Hyper-V that requires HV_HYP_PAGE_SIZE.

> +	void *vaddr;
> +	int i;
> +
> +	if (!pfns)
> +		return NULL;
> +
> +	for (i = 0; i < size / PAGE_SIZE; i++)
> +		pfns[i] = virt_to_hvpfn(addr + i * PAGE_SIZE) +

Use virt_to_pfn(), not virt_to_hvpfn(), for the same reason.

> +			(ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);
> +
> +	vaddr = vmap_pfn(pfns, size / PAGE_SIZE, PAGE_KERNEL_IO);
> +	kfree(pfns);
> +
> +	return vaddr;
> +}
> +
> +void hv_unmap_memory(void *addr)
> +{
> +	vunmap(addr);
> +}
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index b77f4caee3ee..627fcf8d443c 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -252,6 +252,8 @@ int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
>  int hv_mark_gpa_visibility(u16 count, const u64 pfn[],
>  			   enum hv_mem_host_visibility visibility);
>  int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible);
> +void *hv_map_memory(void *addr, unsigned long size);
> +void hv_unmap_memory(void *addr);
>  void hv_sint_wrmsrl_ghcb(u64 msr, u64 value);
>  void hv_sint_rdmsrl_ghcb(u64 msr, u64 *value);
>  void hv_signal_eom_ghcb(void);
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index ff08dc463634..e2db0b8ed938 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -30,6 +30,7 @@
>  #include <asm/processor-flags.h>
>  #include <asm/msr.h>
>  #include <asm/cmdline.h>
> +#include <asm/mshyperv.h>
> 
>  #include "mm_internal.h"
> 
> @@ -202,7 +203,7 @@ void __init sev_setup_arch(void)
>  	phys_addr_t total_mem = memblock_phys_mem_size();
>  	unsigned long size;
> 
> -	if (!sev_active())
> +	if (!sev_active() && !hv_is_isolation_supported())
>  		return;
> 
>  	/*
> diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
> index 54f9aa7e8457..43bd031aa332 100644
> --- a/arch/x86/xen/pci-swiotlb-xen.c
> +++ b/arch/x86/xen/pci-swiotlb-xen.c
> @@ -4,6 +4,7 @@
> 
>  #include <linux/dma-map-ops.h>
>  #include <linux/pci.h>
> +#include <linux/hyperv.h>
>  #include <xen/swiotlb-xen.h>
> 
>  #include <asm/xen/hypervisor.h>
> @@ -91,6 +92,6 @@ int pci_xen_swiotlb_init_late(void)
>  EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
> 
>  IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
> -		  NULL,
> +		  hyperv_swiotlb_detect,
>  		  pci_xen_swiotlb_init,
>  		  NULL);
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 57bbbaa4e8f7..f068e22a5636 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -23,6 +23,7 @@
>  #include <linux/cpu.h>
>  #include <linux/sched/task_stack.h>
> 
> +#include <linux/dma-map-ops.h>
>  #include <linux/delay.h>
>  #include <linux/notifier.h>
>  #include <linux/panic_notifier.h>
> @@ -2081,6 +2082,7 @@ struct hv_device *vmbus_device_create(const guid_t *type,
>  	return child_device_obj;
>  }
> 
> +static u64 vmbus_dma_mask = DMA_BIT_MASK(64);
>  /*
>   * vmbus_device_register - Register the child device
>   */
> @@ -2121,6 +2123,7 @@ int vmbus_device_register(struct hv_device *child_device_obj)
>  	}
>  	hv_debug_add_dev_dir(child_device_obj);
> 
> +	child_device_obj->device.dma_mask = &vmbus_dma_mask;
>  	return 0;
> 
>  err_kset_unregister:
> diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
> index e285a220c913..899563551574 100644
> --- a/drivers/iommu/hyperv-iommu.c
> +++ b/drivers/iommu/hyperv-iommu.c
> @@ -13,14 +13,22 @@
>  #include <linux/irq.h>
>  #include <linux/iommu.h>
>  #include <linux/module.h>
> +#include <linux/hyperv.h>
> +#include <linux/io.h>
> 
>  #include <asm/apic.h>
>  #include <asm/cpu.h>
>  #include <asm/hw_irq.h>
>  #include <asm/io_apic.h>
> +#include <asm/iommu.h>
> +#include <asm/iommu_table.h>
>  #include <asm/irq_remapping.h>
>  #include <asm/hypervisor.h>
>  #include <asm/mshyperv.h>
> +#include <asm/swiotlb.h>
> +#include <linux/dma-map-ops.h>
> +#include <linux/dma-direct.h>
> +#include <linux/set_memory.h>
> 
>  #include "irq_remapping.h"
> 
> @@ -36,6 +44,9 @@
>  static cpumask_t ioapic_max_cpumask = { CPU_BITS_NONE };
>  static struct irq_domain *ioapic_ir_domain;
> 
> +static unsigned long hyperv_io_tlb_size;
> +static void *hyperv_io_tlb_start;
> +
>  static int hyperv_ir_set_affinity(struct irq_data *data,
>  		const struct cpumask *mask, bool force)
>  {
> @@ -337,4 +348,54 @@ static const struct irq_domain_ops hyperv_root_ir_domain_ops = {
>  	.free = hyperv_root_irq_remapping_free,
>  };
> 
> +void __init hyperv_iommu_swiotlb_init(void)
> +{
> +	/*
> +	 * Allocate Hyper-V swiotlb bounce buffer at early place
> +	 * to reserve large contiguous memory.
> +	 */
> +	hyperv_io_tlb_size = swiotlb_size_or_default();
> +	hyperv_io_tlb_start = memblock_alloc(
> +		hyperv_io_tlb_size, HV_HYP_PAGE_SIZE);

Could the alignment be specified as just PAGE_SIZE?  I don't
see any particular relationship here to the Hyper-V page size.

> +
> +	if (!hyperv_io_tlb_start) {
> +		pr_warn("Fail to allocate Hyper-V swiotlb buffer.\n");
> +		return;
> +	}
> +}
> +
> +int __init hyperv_swiotlb_detect(void)
> +{
> +	if (hypervisor_is_type(X86_HYPER_MS_HYPERV)
> +	    && hv_is_isolation_supported()) {
> +		/*
> +		 * Enable swiotlb force mode in Isolation VM to
> +		 * use swiotlb bounce buffer for dma transaction.
> +		 */
> +		swiotlb_force = SWIOTLB_FORCE;
> +
> +		dma_memory_generic_decrypted_ops.map = hv_map_memory;
> +		dma_memory_generic_decrypted_ops.unmap = hv_unmap_memory;
> +		return 1;
> +	}
> +
> +	return 0;
> +}
> +
> +void __init hyperv_iommu_swiotlb_later_init(void)
> +{
> +	/*
> +	 * Swiotlb bounce buffer needs to be mapped in extra address
> +	 * space. Map function doesn't work in the early place and so
> +	 * call swiotlb_late_init_with_tbl() here.
> +	 */
> +	if (swiotlb_late_init_with_tbl(hyperv_io_tlb_start,
> +				       hyperv_io_tlb_size >> IO_TLB_SHIFT))
> +		panic("Fail to initialize hyperv swiotlb.\n");
> +}
> +
> +IOMMU_INIT_FINISH(hyperv_swiotlb_detect,
> +		  NULL, hyperv_iommu_swiotlb_init,
> +		  hyperv_iommu_swiotlb_later_init);
> +
>  #endif
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index 757e09606fd3..724a735d722a 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1739,6 +1739,7 @@ int hyperv_write_cfg_blk(struct pci_dev *dev, void *buf, unsigned int len,
>  int hyperv_reg_block_invalidate(struct pci_dev *dev, void *context,
>  				void (*block_invalidate)(void *context,
>  							 u64 block_mask));
> +int __init hyperv_swiotlb_detect(void);
> 
>  struct hyperv_pci_block_ops {
>  	int (*read_block)(struct pci_dev *dev, void *buf, unsigned int buf_len,
> --
> 2.25.1
diff mbox series

Patch

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index e761c67e2218..84563b3c9f3a 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -294,3 +294,31 @@  int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible)
 
 	return __hv_set_mem_host_visibility((void *)addr, numpages, visibility);
 }
+
+/*
+ * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
+ */
+void *hv_map_memory(void *addr, unsigned long size)
+{
+	unsigned long *pfns = kcalloc(size / HV_HYP_PAGE_SIZE,
+				      sizeof(unsigned long), GFP_KERNEL);
+	void *vaddr;
+	int i;
+
+	if (!pfns)
+		return NULL;
+
+	for (i = 0; i < size / PAGE_SIZE; i++)
+		pfns[i] = virt_to_hvpfn(addr + i * PAGE_SIZE) +
+			(ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);
+
+	vaddr = vmap_pfn(pfns, size / PAGE_SIZE, PAGE_KERNEL_IO);
+	kfree(pfns);
+
+	return vaddr;
+}
+
+void hv_unmap_memory(void *addr)
+{
+	vunmap(addr);
+}
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index b77f4caee3ee..627fcf8d443c 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -252,6 +252,8 @@  int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
 int hv_mark_gpa_visibility(u16 count, const u64 pfn[],
 			   enum hv_mem_host_visibility visibility);
 int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible);
+void *hv_map_memory(void *addr, unsigned long size);
+void hv_unmap_memory(void *addr);
 void hv_sint_wrmsrl_ghcb(u64 msr, u64 value);
 void hv_sint_rdmsrl_ghcb(u64 msr, u64 *value);
 void hv_signal_eom_ghcb(void);
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index ff08dc463634..e2db0b8ed938 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -30,6 +30,7 @@ 
 #include <asm/processor-flags.h>
 #include <asm/msr.h>
 #include <asm/cmdline.h>
+#include <asm/mshyperv.h>
 
 #include "mm_internal.h"
 
@@ -202,7 +203,7 @@  void __init sev_setup_arch(void)
 	phys_addr_t total_mem = memblock_phys_mem_size();
 	unsigned long size;
 
-	if (!sev_active())
+	if (!sev_active() && !hv_is_isolation_supported())
 		return;
 
 	/*
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index 54f9aa7e8457..43bd031aa332 100644
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -4,6 +4,7 @@ 
 
 #include <linux/dma-map-ops.h>
 #include <linux/pci.h>
+#include <linux/hyperv.h>
 #include <xen/swiotlb-xen.h>
 
 #include <asm/xen/hypervisor.h>
@@ -91,6 +92,6 @@  int pci_xen_swiotlb_init_late(void)
 EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
 
 IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
-		  NULL,
+		  hyperv_swiotlb_detect,
 		  pci_xen_swiotlb_init,
 		  NULL);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 57bbbaa4e8f7..f068e22a5636 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -23,6 +23,7 @@ 
 #include <linux/cpu.h>
 #include <linux/sched/task_stack.h>
 
+#include <linux/dma-map-ops.h>
 #include <linux/delay.h>
 #include <linux/notifier.h>
 #include <linux/panic_notifier.h>
@@ -2081,6 +2082,7 @@  struct hv_device *vmbus_device_create(const guid_t *type,
 	return child_device_obj;
 }
 
+static u64 vmbus_dma_mask = DMA_BIT_MASK(64);
 /*
  * vmbus_device_register - Register the child device
  */
@@ -2121,6 +2123,7 @@  int vmbus_device_register(struct hv_device *child_device_obj)
 	}
 	hv_debug_add_dev_dir(child_device_obj);
 
+	child_device_obj->device.dma_mask = &vmbus_dma_mask;
 	return 0;
 
 err_kset_unregister:
diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
index e285a220c913..899563551574 100644
--- a/drivers/iommu/hyperv-iommu.c
+++ b/drivers/iommu/hyperv-iommu.c
@@ -13,14 +13,22 @@ 
 #include <linux/irq.h>
 #include <linux/iommu.h>
 #include <linux/module.h>
+#include <linux/hyperv.h>
+#include <linux/io.h>
 
 #include <asm/apic.h>
 #include <asm/cpu.h>
 #include <asm/hw_irq.h>
 #include <asm/io_apic.h>
+#include <asm/iommu.h>
+#include <asm/iommu_table.h>
 #include <asm/irq_remapping.h>
 #include <asm/hypervisor.h>
 #include <asm/mshyperv.h>
+#include <asm/swiotlb.h>
+#include <linux/dma-map-ops.h>
+#include <linux/dma-direct.h>
+#include <linux/set_memory.h>
 
 #include "irq_remapping.h"
 
@@ -36,6 +44,9 @@ 
 static cpumask_t ioapic_max_cpumask = { CPU_BITS_NONE };
 static struct irq_domain *ioapic_ir_domain;
 
+static unsigned long hyperv_io_tlb_size;
+static void *hyperv_io_tlb_start;
+
 static int hyperv_ir_set_affinity(struct irq_data *data,
 		const struct cpumask *mask, bool force)
 {
@@ -337,4 +348,54 @@  static const struct irq_domain_ops hyperv_root_ir_domain_ops = {
 	.free = hyperv_root_irq_remapping_free,
 };
 
+void __init hyperv_iommu_swiotlb_init(void)
+{
+	/*
+	 * Allocate Hyper-V swiotlb bounce buffer at early place
+	 * to reserve large contiguous memory.
+	 */
+	hyperv_io_tlb_size = swiotlb_size_or_default();
+	hyperv_io_tlb_start = memblock_alloc(
+		hyperv_io_tlb_size, HV_HYP_PAGE_SIZE);
+
+	if (!hyperv_io_tlb_start) {
+		pr_warn("Fail to allocate Hyper-V swiotlb buffer.\n");
+		return;
+	}
+}
+
+int __init hyperv_swiotlb_detect(void)
+{
+	if (hypervisor_is_type(X86_HYPER_MS_HYPERV)
+	    && hv_is_isolation_supported()) {
+		/*
+		 * Enable swiotlb force mode in Isolation VM to
+		 * use swiotlb bounce buffer for dma transaction.
+		 */
+		swiotlb_force = SWIOTLB_FORCE;
+
+		dma_memory_generic_decrypted_ops.map = hv_map_memory;
+		dma_memory_generic_decrypted_ops.unmap = hv_unmap_memory;
+		return 1;
+	}
+
+	return 0;
+}
+
+void __init hyperv_iommu_swiotlb_later_init(void)
+{
+	/*
+	 * Swiotlb bounce buffer needs to be mapped in extra address
+	 * space. Map function doesn't work in the early place and so
+	 * call swiotlb_late_init_with_tbl() here.
+	 */
+	if (swiotlb_late_init_with_tbl(hyperv_io_tlb_start,
+				       hyperv_io_tlb_size >> IO_TLB_SHIFT))
+		panic("Fail to initialize hyperv swiotlb.\n");
+}
+
+IOMMU_INIT_FINISH(hyperv_swiotlb_detect,
+		  NULL, hyperv_iommu_swiotlb_init,
+		  hyperv_iommu_swiotlb_later_init);
+
 #endif
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 757e09606fd3..724a735d722a 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1739,6 +1739,7 @@  int hyperv_write_cfg_blk(struct pci_dev *dev, void *buf, unsigned int len,
 int hyperv_reg_block_invalidate(struct pci_dev *dev, void *context,
 				void (*block_invalidate)(void *context,
 							 u64 block_mask));
+int __init hyperv_swiotlb_detect(void);
 
 struct hyperv_pci_block_ops {
 	int (*read_block)(struct pci_dev *dev, void *buf, unsigned int buf_len,