linux-kernel - [PATCH] Drivers: hv: Use nested hypercall for post message and signal event

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Date:   Mon,  3 Apr 2023 16:22:58 -0700
From:   Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To:     linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     mikelley@...rosoft.com, kys@...rosoft.com, wei.liu@...nel.org,
        haiyangz@...rosoft.com, decui@...rosoft.com
Subject: [PATCH] Drivers: hv: Use nested hypercall for post message and signal event

When running nested, these hypercalls must be sent to the L0 hypervisor
or vmbus will fail.
Only relevant for x86; nested functionality is not available in ARM64.

Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
---
 drivers/hv/connection.c | 4 ++++
 drivers/hv/hv.c         | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 9dc27e5d367a..04bf7f168976 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -539,6 +539,10 @@ void vmbus_set_event(struct vmbus_channel *channel)
 	if (hv_isolation_type_snp())
 		hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
 				NULL, sizeof(channel->sig_event));
+#if defined(CONFIG_X86_64)
+	else if (hv_nested)
+		hv_do_fast_nested_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
+#endif
 	else
 		hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 }
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 8b0dd8e5244d..c7f7652932ca 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -102,6 +102,11 @@ int hv_post_message(union hv_connection_id connection_id,
 		status = hv_ghcb_hypercall(HVCALL_POST_MESSAGE,
 				(void *)aligned_msg, NULL,
 				sizeof(*aligned_msg));
+#if defined(CONFIG_X86_64)
+	else if (hv_nested)
+		status = hv_do_nested_hypercall(HVCALL_POST_MESSAGE,
+				aligned_msg, NULL);
+#endif
 	else
 		status = hv_do_hypercall(HVCALL_POST_MESSAGE,
 				aligned_msg, NULL);
-- 
2.25.1