[PATCH v2 1/6] x86/sev: Define the #HV doorbell page structure

[Melody Wang]

Restricted injection is a feature which enforces additional interrupt and event
injection security protections for a SEV-SNP guest. It disables all
hypervisor-based interrupt queuing and event injection of all vectors except
a new exception vector, #HV (28), which is reserved for SNP guest use, but
never generated by hardware. #HV is only allowed to be injected into VMSAs that
execute with Restricted Injection.

The guests running with the SNP restricted injection feature active limit the
host to ringing a doorbell with a #HV exception.

Define two fields in the #HV doorbell page: a pending event field, and an
EOI assist.

Create the structure definition for the #HV doorbell page as per GHCB
specification.

Co-developed-by: Thomas Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Thomas Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Melody Wang <huibo.wang@xxxxxxx>
---
 arch/x86/include/asm/svm.h | 41 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index f0dea3750ca9..2b1f4c8daf19 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -516,6 +516,47 @@ struct ghcb {
 	u32 ghcb_usage;
 } __packed;
 
+/*
+ * Hypervisor doorbell page:
+ *
+ * Used when restricted injection is enabled for a VM. One page in size that
+ * is shared between the guest and hypervisor to communicate exception and
+ * interrupt events.
+ */
+struct hvdb_events {
+	/* First 64 bytes of HV doorbell page defined in GHCB specification */
+	union {
+		struct {
+			/* Interrupt vector being injected */
+			u8 vector;
+
+			/* Non-maskable event field (NMI, etc.) */
+			u8 nm_events;
+		};
+
+		struct {
+			/* Non-maskable event indicators */
+			u16 reserved1:		8,
+			    nmi:		1,
+			    mce:		1,
+			    reserved2:		5,
+			    no_further_signal:	1;
+		};
+
+		u16 pending_events;
+	};
+
+	u8 no_eoi_required;
+
+	u8 reserved3[61];
+};
+
+struct hvdb {
+	struct hvdb_events events;
+
+	/* Remainder of the page is for software use */
+	u8 reserved[PAGE_SIZE - sizeof(struct hvdb_events)];
+};
 
 #define EXPECTED_VMCB_SAVE_AREA_SIZE		744
 #define EXPECTED_GHCB_SAVE_AREA_SIZE		1032
-- 
2.34.1