linux-kernel - [PATCH v3 1/7] x86/sev: Define the #HV doorbell page structure

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Message-ID: <20241127225539.5567-2-huibo.wang@amd.com>
Date: Wed, 27 Nov 2024 22:55:33 +0000
From: Melody Wang <huibo.wang@....com>
To: <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini
	<pbonzini@...hat.com>, Tom Lendacky <thomas.lendacky@....com>, "Neeraj
 Upadhyay" <neeraj.upadhyay@....com>, Ashish Kalra <ashish.kalra@....com>,
	Michael Roth <michael.roth@....com>, Pankaj Gupta <pankaj.gupta@....com>,
	Melody Wang <huibo.wang@....com>
Subject: [PATCH v3 1/7] x86/sev: Define the #HV doorbell page structure

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@....com>
Signed-off-by: Thomas Lendacky <thomas.lendacky@....com>
Signed-off-by: Melody Wang <huibo.wang@....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 2b59b9951c90..95cb9a62f477 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -239,6 +239,39 @@ 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)
-- 
2.34.1