[PATCH V5 06/12] x86/hyperv: Add ghcb hvcall support for SNP VM

Tianyu Lan
2021-09-14T13:39:51Z

From: Tianyu Lan <Tianyu.Lan@microsoft.com>

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@microsoft.com>
---
Change since v3:
* Add hv_ghcb_hypercall() stub function to avoid
compile error for ARM.
---
arch/x86/hyperv/ivm.c | 74 ++++++++++++++++++++++++++++++++++
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, 93 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 5439723446c9..dfdac3a40036 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -18,10 +18,84 @@
#include <asm/mshyperv.h>
#include <asm/hypervisor.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;
+ u64 status;
+
+ 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));
+
+ status = hv_ghcb->hypercall.hypercalloutput.callstatus;
+
+ local_irq_restore(flags);
+
+ return status;
+}
+
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..8820ae68f20f 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(channel->sig_event));
+ 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 dee1a96bc535..5644ba2bfa5c 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(*aligned_msg));
+ 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 94750bafd4cc..a0ec607a2fd6 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