Commit a494aef2 authored by Dexuan Cui's avatar Dexuan Cui Committed by Wei Liu
Browse files

PCI: hv: Replace retarget_msi_interrupt_params with hyperv_pcpu_input_arg 



4 commits are involved here:
A (2016): commit 0de8ce3e ("PCI: hv: Allocate physically contiguous hypercall params buffer")
B (2017): commit be66b673 ("PCI: hv: Use page allocation for hbus structure")
C (2019): commit 877b911a ("PCI: hv: Avoid a kmemleak false positive caused by the hbus buffer")
D (2018): commit 68bb7bfb ("X86/Hyper-V: Enable IPI enlightenments")

Patch D introduced the per-CPU hypercall input page "hyperv_pcpu_input_arg"
in 2018. With patch D, we no longer need the per-Hyper-V-PCI-bus hypercall
input page "hbus->retarget_msi_interrupt_params" that was added in patch A,
and the issue addressed by patch B is no longer an issue, and we can also
get rid of patch C.

The change here is required for PCI device assignment to work for
Confidential VMs (CVMs) running without a paravisor, because otherwise we
would have to call set_memory_decrypted() for
"hbus->retarget_msi_interrupt_params" before calling the hypercall
HVCALL_RETARGET_INTERRUPT.

Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Acked-by: default avatarLorenzo Pieralisi <lpieralisi@kernel.org>
Link: https://lore.kernel.org/r/20230421013025.17152-1-decui@microsoft.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 9c318a1d

drivers/pci/controller/pci-hyperv.c

+7 −41
Original line number Diff line number Diff line
@@ -508,20 +508,11 @@ struct hv_pcibus_device { 
	struct msi_domain_info msi_info;

	struct irq_domain *irq_domain;



	spinlock_t retarget_msi_interrupt_lock;



	struct workqueue_struct *wq;



	/* Highest slot of child device with resources allocated */

	int wslot_res_allocated;

	bool use_calls; /* Use hypercalls to access mmio cfg space */



	/* hypercall arg, must not cross page boundary */

	struct hv_retarget_device_interrupt retarget_msi_interrupt_params;



	/*

	 * Don't put anything here: retarget_msi_interrupt_params must be last

	 */

};



/*
@@ -645,9 +636,9 @@ static void hv_arch_irq_unmask(struct irq_data *data) 
	hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);

	int_desc = data->chip_data;



	spin_lock_irqsave(&hbus->retarget_msi_interrupt_lock, flags);

	local_irq_save(flags);



	params = &hbus->retarget_msi_interrupt_params;

	params = *this_cpu_ptr(hyperv_pcpu_input_arg);

	memset(params, 0, sizeof(*params));

	params->partition_id = HV_PARTITION_ID_SELF;

	params->int_entry.source = HV_INTERRUPT_SOURCE_MSI;
@@ -680,7 +671,7 @@ static void hv_arch_irq_unmask(struct irq_data *data) 


		if (!alloc_cpumask_var(&tmp, GFP_ATOMIC)) {

			res = 1;

			goto exit_unlock;

			goto out;

		}



		cpumask_and(tmp, dest, cpu_online_mask);
@@ -689,7 +680,7 @@ static void hv_arch_irq_unmask(struct irq_data *data) 


		if (nr_bank <= 0) {

			res = 1;

			goto exit_unlock;

			goto out;

		}



		/*
@@ -708,8 +699,8 @@ static void hv_arch_irq_unmask(struct irq_data *data) 
	res = hv_do_hypercall(HVCALL_RETARGET_INTERRUPT | (var_size << 17),

			      params, NULL);



exit_unlock:

	spin_unlock_irqrestore(&hbus->retarget_msi_interrupt_lock, flags);

out:

	local_irq_restore(flags);



	/*

	 * During hibernation, when a CPU is offlined, the kernel tries
@@ -3598,35 +3589,11 @@ static int hv_pci_probe(struct hv_device *hdev, 
	bool enter_d0_retry = true;

	int ret;



	/*

	 * hv_pcibus_device contains the hypercall arguments for retargeting in

	 * hv_irq_unmask(). Those must not cross a page boundary.

	 */

	BUILD_BUG_ON(sizeof(*hbus) > HV_HYP_PAGE_SIZE);



	bridge = devm_pci_alloc_host_bridge(&hdev->device, 0);

	if (!bridge)

		return -ENOMEM;



	/*

	 * With the recent 59bb47985c1d ("mm, sl[aou]b: guarantee natural

	 * alignment for kmalloc(power-of-two)"), kzalloc() is able to allocate

	 * a 4KB buffer that is guaranteed to be 4KB-aligned. Here the size and

	 * alignment of hbus is important because hbus's field

	 * retarget_msi_interrupt_params must not cross a 4KB page boundary.

	 *

	 * Here we prefer kzalloc to get_zeroed_page(), because a buffer

	 * allocated by the latter is not tracked and scanned by kmemleak, and

	 * hence kmemleak reports the pointer contained in the hbus buffer

	 * (i.e. the hpdev struct, which is created in new_pcichild_device() and

	 * is tracked by hbus->children) as memory leak (false positive).

	 *

	 * If the kernel doesn't have 59bb47985c1d, get_zeroed_page() *must* be

	 * used to allocate the hbus buffer and we can avoid the kmemleak false

	 * positive by using kmemleak_alloc() and kmemleak_free() to ask

	 * kmemleak to track and scan the hbus buffer.

	 */

	hbus = kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);

	hbus = kzalloc(sizeof(*hbus), GFP_KERNEL);

	if (!hbus)

		return -ENOMEM;
@@ -3683,7 +3650,6 @@ static int hv_pci_probe(struct hv_device *hdev, 
	INIT_LIST_HEAD(&hbus->dr_list);

	spin_lock_init(&hbus->config_lock);

	spin_lock_init(&hbus->device_list_lock);

	spin_lock_init(&hbus->retarget_msi_interrupt_lock);

	hbus->wq = alloc_ordered_workqueue("hv_pci_%x", 0,

					   hbus->bridge->domain_nr);

	if (!hbus->wq) {