4 commits are involved here:
A (2016): commit 0de8ce3ee8e3 ("PCI: hv: Allocate physically contiguous hypercall params buffer")
B (2017): commit be66b6736591 ("PCI: hv: Use page allocation for hbus structure")
C (2019): commit 877b911a5ba0 ("PCI: hv: Avoid a kmemleak false positive caused by the hbus buffer")
D (2018): commit 68bb7bfb7985 ("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: Dexuan Cui <decui@xxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
---
Changes in v2:
Fixed the inaccuracy in the commit message (Thanks Michael):
"Confidential VMs (CVMs)" -> "Confidential VMs (CVMs) running without a paravisor".
Added Michael's Reviewed-by.
drivers/pci/controller/pci-hyperv.c | 48 +++++------------------------
1 file changed, 7 insertions(+), 41 deletions(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 337f3b4a04fc0..bc32662c6bb7f 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -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) {
--
2.25.1
