[PATCH v4 1/7] x86/sev: Define the #HV doorbell page structure

Melody Wang
2026-04-24T17:43:04Z

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@amd.com>
Signed-off-by: Thomas Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Melody Wang <huibo.wang@amd.com>
---
arch/x86/include/asm/svm.h | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index bcfeb5e7c0ed..9822b0b346ae 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -252,6 +252,39 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
#define SVM_TSC_RATIO_MAX 0x000000ffffffffffULL
#define SVM_TSC_RATIO_DEFAULT 0x0100000000ULL

+/*
+ * 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 {
+ /* Non-maskable event indicators */
+ u16 vector: 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)];
+};

/* AVIC */
#define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK (0xFFULL)
--
2.43.0