[PATCH hyperv-next v3 11/15] Drivers: hv: Functions for setting up and tearing down the paravisor SynIC
From: Roman Kisel
Date: Tue Jun 03 2025 - 20:46:19 EST
The confidential VMBus runs with the paravisor SynIC and requires
configuring it with the paravisor.
Add the functions for configuring the paravisor SynIC
Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
---
drivers/hv/hv.c | 180 +++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 169 insertions(+), 11 deletions(-)
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 2b561825089a..c9649ab3439e 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -203,7 +203,7 @@ int hv_synic_alloc(void)
decrypt, "hypervisor SynIC event");
if (ret)
goto err;
- }
+ }
if (vmbus_is_confidential()) {
ret = hv_alloc_page(cpu, &hv_cpu->para_synic_message_page,
@@ -267,7 +267,6 @@ void hv_hyp_synic_enable_regs(unsigned int cpu)
union hv_synic_simp simp;
union hv_synic_siefp siefp;
union hv_synic_sint shared_sint;
- union hv_synic_scontrol sctrl;
/* Setup the Synic's message page */
simp.as_uint64 = hv_get_msr(HV_MSR_SIMP);
@@ -288,7 +287,7 @@ void hv_hyp_synic_enable_regs(unsigned int cpu)
hv_set_msr(HV_MSR_SIMP, simp.as_uint64);
- /* Setup the Synic's event page */
+ /* Setup the Synic's event page with the hypervisor. */
siefp.as_uint64 = hv_get_msr(HV_MSR_SIEFP);
siefp.siefp_enabled = 1;
@@ -316,6 +315,11 @@ void hv_hyp_synic_enable_regs(unsigned int cpu)
shared_sint.masked = false;
shared_sint.auto_eoi = hv_recommend_using_aeoi();
hv_set_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
+}
+
+static void hv_hyp_synic_enable_interrupts(void)
+{
+ union hv_synic_scontrol sctrl;
/* Enable the global synic bit */
sctrl.as_uint64 = hv_get_msr(HV_MSR_SCONTROL);
@@ -324,13 +328,90 @@ void hv_hyp_synic_enable_regs(unsigned int cpu)
hv_set_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
}
+/*
+ * The paravisor might not support proxying SynIC, and this
+ * function may fail.
+ */
+static int hv_para_synic_enable_regs(unsigned int cpu)
+{
+ int err;
+ union hv_synic_simp simp;
+ union hv_synic_siefp siefp;
+ struct hv_per_cpu_context *hv_cpu
+ = per_cpu_ptr(hv_context.cpu_context, cpu);
+
+ /* Setup the Synic's message page with the paravisor. */
+ err = hv_para_get_synic_register(HV_MSR_SIMP, &simp.as_uint64);
+ if (err)
+ return err;
+ simp.simp_enabled = 1;
+ simp.base_simp_gpa = virt_to_phys(hv_cpu->para_synic_message_page)
+ >> HV_HYP_PAGE_SHIFT;
+ err = hv_para_set_synic_register(HV_MSR_SIMP, simp.as_uint64);
+ if (err)
+ return err;
+
+ /* Setup the Synic's event page with the paravisor. */
+ err = hv_para_get_synic_register(HV_MSR_SIEFP, &siefp.as_uint64);
+ if (err)
+ return err;
+ siefp.siefp_enabled = 1;
+ siefp.base_siefp_gpa = virt_to_phys(hv_cpu->para_synic_event_page)
+ >> HV_HYP_PAGE_SHIFT;
+ return hv_para_set_synic_register(HV_MSR_SIEFP, siefp.as_uint64);
+}
+
+static int hv_para_synic_enable_interrupts(void)
+{
+ union hv_synic_scontrol sctrl;
+ int err;
+
+ /* Enable the global synic bit */
+ err = hv_para_get_synic_register(HV_MSR_SCONTROL, &sctrl.as_uint64);
+ if (err)
+ return err;
+ sctrl.enable = 1;
+
+ return hv_para_set_synic_register(HV_MSR_SCONTROL, sctrl.as_uint64);
+}
+
int hv_synic_init(unsigned int cpu)
{
+ int err;
+
+ /*
+ * The paravisor may not support the confidential VMBus,
+ * check on that first.
+ */
+ if (vmbus_is_confidential()) {
+ err = hv_para_synic_enable_regs(cpu);
+ if (err)
+ goto fail;
+ }
+
hv_hyp_synic_enable_regs(cpu);
+ if (vmbus_is_confidential()) {
+ err = hv_para_synic_enable_interrupts();
+ if (err)
+ goto fail;
+ } else
+ hv_hyp_synic_enable_interrupts();
hv_stimer_legacy_init(cpu, VMBUS_MESSAGE_SINT);
return 0;
+
+fail:
+ /*
+ * The failure may only come from enabling the paravisor SynIC.
+ * That in turn means that the confidential VMBus cannot be used
+ * which is not an error: the setup will be re-tried with the
+ * non-confidential VMBus.
+ *
+ * We also don't bother attempting to reset the paravisor registers
+ * as something isn't working there anyway.
+ */
+ return err;
}
void hv_hyp_synic_disable_regs(unsigned int cpu)
@@ -340,7 +421,6 @@ void hv_hyp_synic_disable_regs(unsigned int cpu)
union hv_synic_sint shared_sint;
union hv_synic_simp simp;
union hv_synic_siefp siefp;
- union hv_synic_scontrol sctrl;
shared_sint.as_uint64 = hv_get_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT);
@@ -378,14 +458,71 @@ void hv_hyp_synic_disable_regs(unsigned int cpu)
}
hv_set_msr(HV_MSR_SIEFP, siefp.as_uint64);
+}
+
+static void hv_hyp_synic_disable_interrupts(void)
+{
+ union hv_synic_scontrol sctrl;
/* Disable the global synic bit */
sctrl.as_uint64 = hv_get_msr(HV_MSR_SCONTROL);
sctrl.enable = 0;
hv_set_msr(HV_MSR_SCONTROL, sctrl.as_uint64);
+}
- if (vmbus_irq != -1)
- disable_percpu_irq(vmbus_irq);
+static void hv_para_synic_disable_regs(unsigned int cpu)
+{
+ /*
+ * When a get/set register error is encountered, the function
+ * returns as the paravisor may not support these registers.
+ */
+ int err;
+ union hv_synic_simp simp;
+ union hv_synic_siefp siefp;
+
+ struct hv_per_cpu_context *hv_cpu
+ = per_cpu_ptr(hv_context.cpu_context, cpu);
+
+ /* Disable SynIC's message page in the paravisor. */
+ err = hv_para_get_synic_register(HV_MSR_SIMP, &simp.as_uint64);
+ if (err)
+ return;
+ simp.simp_enabled = 0;
+
+ if (hv_cpu->para_synic_message_page) {
+ free_page((u64)(hv_cpu->para_synic_message_page));
+ hv_cpu->para_synic_message_page = NULL;
+ }
+
+ err = hv_para_set_synic_register(HV_MSR_SIMP, simp.as_uint64);
+ if (err)
+ return;
+
+ /* Disable SynIC's event page in the paravisor. */
+ err = hv_para_get_synic_register(HV_MSR_SIEFP, &siefp.as_uint64);
+ if (err)
+ return;
+ siefp.siefp_enabled = 0;
+
+ if (hv_cpu->para_synic_event_page) {
+ free_page((u64)(hv_cpu->para_synic_event_page));
+ hv_cpu->para_synic_event_page = NULL;
+ }
+
+ hv_para_set_synic_register(HV_MSR_SIEFP, siefp.as_uint64);
+}
+
+static void hv_para_synic_disable_interrupts(void)
+{
+ union hv_synic_scontrol sctrl;
+ int err;
+
+ /* Disable the global synic bit */
+ err = hv_para_get_synic_register(HV_MSR_SCONTROL, &sctrl.as_uint64);
+ if (err)
+ return;
+ sctrl.enable = 0;
+ hv_para_set_synic_register(HV_MSR_SCONTROL, sctrl.as_uint64);
}
#define HV_MAX_TRIES 3
@@ -398,16 +535,18 @@ void hv_hyp_synic_disable_regs(unsigned int cpu)
* that the normal interrupt handling mechanism will find and process the channel interrupt
* "very soon", and in the process clear the bit.
*/
-static bool hv_synic_event_pending(void)
+static bool __hv_synic_event_pending(union hv_synic_event_flags *event, int sint)
{
- struct hv_per_cpu_context *hv_cpu = this_cpu_ptr(hv_context.cpu_context);
- union hv_synic_event_flags *event =
- (union hv_synic_event_flags *)hv_cpu->hyp_synic_event_page + VMBUS_MESSAGE_SINT;
- unsigned long *recv_int_page = event->flags; /* assumes VMBus version >= VERSION_WIN8 */
+ unsigned long *recv_int_page;
bool pending;
u32 relid;
int tries = 0;
+ if (!event)
+ return false;
+
+ event += sint;
+ recv_int_page = event->flags; /* assumes VMBus version >= VERSION_WIN8 */
retry:
pending = false;
for_each_set_bit(relid, recv_int_page, HV_EVENT_FLAGS_COUNT) {
@@ -424,6 +563,17 @@ static bool hv_synic_event_pending(void)
return pending;
}
+static bool hv_synic_event_pending(void)
+{
+ struct hv_per_cpu_context *hv_cpu = this_cpu_ptr(hv_context.cpu_context);
+ union hv_synic_event_flags *hyp_synic_event_page = hv_cpu->hyp_synic_event_page;
+ union hv_synic_event_flags *para_synic_event_page = hv_cpu->para_synic_event_page;
+
+ return
+ __hv_synic_event_pending(hyp_synic_event_page, VMBUS_MESSAGE_SINT) ||
+ __hv_synic_event_pending(para_synic_event_page, VMBUS_MESSAGE_SINT);
+}
+
static int hv_pick_new_cpu(struct vmbus_channel *channel)
{
int ret = -EBUSY;
@@ -517,6 +667,14 @@ int hv_synic_cleanup(unsigned int cpu)
hv_stimer_legacy_cleanup(cpu);
hv_hyp_synic_disable_regs(cpu);
+ if (vmbus_is_confidential()) {
+ hv_para_synic_disable_regs(cpu);
+ hv_para_synic_disable_interrupts();
+ } else {
+ hv_hyp_synic_disable_interrupts();
+ }
+ if (vmbus_irq != -1)
+ disable_percpu_irq(vmbus_irq);
return ret;
}
--
2.43.0