[PATCH V4 06/13] hyperv: Add ghcb hvcall support for SNP VM

[Tianyu Lan <ltykernel@xxxxxxxxx>]

From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>

hyperv provides ghcb hvcall to handle VMBus
HVCALL_SIGNAL_EVENT and HVCALL_POST_MESSAGE
msg in SNP Isolation VM. Add such support.

Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
---
Change since v3:
        * Add hv_ghcb_hypercall() stub function to avoid
          compile error for ARM.
---
 arch/x86/hyperv/ivm.c          | 71 ++++++++++++++++++++++++++++++++++
 drivers/hv/connection.c        |  6 ++-
 drivers/hv/hv.c                |  8 +++-
 drivers/hv/hv_common.c         |  6 +++
 include/asm-generic/mshyperv.h |  1 +
 5 files changed, 90 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index f56fe4f73000..e761c67e2218 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -17,10 +17,81 @@
 #include <asm/io.h>
 #include <asm/mshyperv.h>
 
+#define GHCB_USAGE_HYPERV_CALL 1
+
 union hv_ghcb {
        struct ghcb ghcb;
+       struct {
+               u64 hypercalldata[509];
+               u64 outputgpa;
+               union {
+                       union {
+                               struct {
+                                       u32 callcode        : 16;
+                                       u32 isfast          : 1;
+                                       u32 reserved1       : 14;
+                                       u32 isnested        : 1;
+                                       u32 countofelements : 12;
+                                       u32 reserved2       : 4;
+                                       u32 repstartindex   : 12;
+                                       u32 reserved3       : 4;
+                               };
+                               u64 asuint64;
+                       } hypercallinput;
+                       union {
+                               struct {
+                                       u16 callstatus;
+                                       u16 reserved1;
+                                       u32 elementsprocessed : 12;
+                                       u32 reserved2         : 20;
+                               };
+                               u64 asunit64;
+                       } hypercalloutput;
+               };
+               u64 reserved2;
+       } hypercall;
 } __packed __aligned(HV_HYP_PAGE_SIZE);
 
+u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
+{
+       union hv_ghcb *hv_ghcb;
+       void **ghcb_base;
+       unsigned long flags;
+
+       if (!hv_ghcb_pg)
+               return -EFAULT;
+
+       WARN_ON(in_nmi());
+
+       local_irq_save(flags);
+       ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
+       hv_ghcb = (union hv_ghcb *)*ghcb_base;
+       if (!hv_ghcb) {
+               local_irq_restore(flags);
+               return -EFAULT;
+       }
+
+       hv_ghcb->ghcb.protocol_version = GHCB_PROTOCOL_MAX;
+       hv_ghcb->ghcb.ghcb_usage = GHCB_USAGE_HYPERV_CALL;
+
+       hv_ghcb->hypercall.outputgpa = (u64)output;
+       hv_ghcb->hypercall.hypercallinput.asuint64 = 0;
+       hv_ghcb->hypercall.hypercallinput.callcode = control;
+
+       if (input_size)
+               memcpy(hv_ghcb->hypercall.hypercalldata, input, input_size);
+
+       VMGEXIT();
+
+       hv_ghcb->ghcb.ghcb_usage = 0xffffffff;
+       memset(hv_ghcb->ghcb.save.valid_bitmap, 0,
+              sizeof(hv_ghcb->ghcb.save.valid_bitmap));
+
+       local_irq_restore(flags);
+
+       return hv_ghcb->hypercall.hypercalloutput.callstatus;
+}
+
 void hv_ghcb_msr_write(u64 msr, u64 value)
 {
        union hv_ghcb *hv_ghcb;
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 5e479d54918c..6d315c1465e0 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -447,6 +447,10 @@ void vmbus_set_event(struct vmbus_channel *channel)
 
        ++channel->sig_events;
 
-       hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
+       if (hv_isolation_type_snp())
+               hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
+                               NULL, sizeof(u64));
+       else
+               hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 }
 EXPORT_SYMBOL_GPL(vmbus_set_event);
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 97b21256a9db..d4531c64d9d3 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -98,7 +98,13 @@ int hv_post_message(union hv_connection_id connection_id,
        aligned_msg->payload_size = payload_size;
        memcpy((void *)aligned_msg->payload, payload, payload_size);
 
-       status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL);
+       if (hv_isolation_type_snp())
+               status = hv_ghcb_hypercall(HVCALL_POST_MESSAGE,
+                               (void *)aligned_msg, NULL,
+                               sizeof(struct hv_input_post_message));
+       else
+               status = hv_do_hypercall(HVCALL_POST_MESSAGE,
+                               aligned_msg, NULL);
 
        /* Preemption must remain disabled until after the hypercall
         * so some other thread can't get scheduled onto this cpu and
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 1fc82d237161..7be173a99f27 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -289,3 +289,9 @@ void __weak hyperv_cleanup(void)
 {
 }
 EXPORT_SYMBOL_GPL(hyperv_cleanup);
+
+u64 __weak hv_ghcb_hypercall(u64 control, void *input, void *output, u32 
input_size)
+{
+       return HV_STATUS_INVALID_PARAMETER;
+}
+EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 04a687d95eac..0da45807c36a 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -250,6 +250,7 @@ bool hv_is_hibernation_supported(void);
 enum hv_isolation_type hv_get_isolation_type(void);
 bool hv_is_isolation_supported(void);
 bool hv_isolation_type_snp(void);
+u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size);
 void hyperv_cleanup(void);
 bool hv_query_ext_cap(u64 cap_query);
 #else /* CONFIG_HYPERV */
-- 
2.25.1