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Subject[RFC PATCH V4 05/12] HV: Add ghcb hvcall support for SNP VM
Date
From: Tianyu Lan <Tianyu.Lan@microsoft.com>

Hyper-V 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>
---
arch/x86/hyperv/ivm.c | 42 +++++++++++++++++++++++++++++++++
arch/x86/include/asm/mshyperv.h | 1 +
drivers/hv/connection.c | 6 ++++-
drivers/hv/hv.c | 8 ++++++-
include/asm-generic/mshyperv.h | 29 +++++++++++++++++++++++
5 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index c7b54631ca0d..8a6f4e9e3d6c 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -15,6 +15,48 @@
#include <asm/io.h>
#include <asm/mshyperv.h>

+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 (!ms_hyperv.ghcb_base)
+ return -EFAULT;
+
+ WARN_ON(in_nmi());
+
+ local_irq_save(flags);
+ ghcb_base = (void **)this_cpu_ptr(ms_hyperv.ghcb_base);
+ hv_ghcb = (union hv_ghcb *)*ghcb_base;
+ if (!hv_ghcb) {
+ local_irq_restore(flags);
+ return -EFAULT;
+ }
+
+ memset(hv_ghcb, 0x00, HV_HYP_PAGE_SIZE);
+ hv_ghcb->ghcb.protocol_version = 1;
+ hv_ghcb->ghcb.ghcb_usage = 1;
+
+ 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;
+}
+EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
+
void hv_ghcb_msr_write(u64 msr, u64 value)
{
union hv_ghcb *hv_ghcb;
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index f9cc3753040a..fe03e3e833ac 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -258,6 +258,7 @@ void hv_sint_rdmsrl_ghcb(u64 msr, u64 *value);
void hv_signal_eom_ghcb(void);
void hv_ghcb_msr_write(u64 msr, u64 value);
void hv_ghcb_msr_read(u64 msr, u64 *value);
+u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size);

#define hv_get_synint_state_ghcb(int_num, val) \
hv_sint_rdmsrl_ghcb(HV_X64_MSR_SINT0 + int_num, val)
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 311cd005b3be..186fd4c8acd4 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -445,6 +445,10 @@ 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 59f7173c4d9f..e5c9fc467893 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/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index e6d6886faed1..8f6f283fb5b5 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -30,6 +30,35 @@

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(PAGE_SIZE);

struct ms_hyperv_info {
--
2.25.1
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