linux-kernel - [PATCH v5 4/7] KVM: SVM: Software reserved fields

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Date:   Thu,  3 Jun 2021 15:14:37 +0000
From:   Vineeth Pillai <viremana@...ux.microsoft.com>
To:     Lan Tianyu <Tianyu.Lan@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Wei Liu <wei.liu@...nel.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>
Cc:     Vineeth Pillai <viremana@...ux.microsoft.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "K. Y. Srinivasan" <kys@...rosoft.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org
Subject: [PATCH v5 4/7] KVM: SVM: Software reserved fields

SVM added support for certain reserved fields to be used by
software or hypervisor. Add the following reserved fields:
  - VMCB offset 0x3e0 - 0x3ff
  - Clean bit 31
  - SVM intercept exit code 0xf0000000

Later patches will make use of this for supporting Hyper-V
nested virtualization enhancements.

Signed-off-by: Vineeth Pillai <viremana@...ux.microsoft.com>
---
 arch/x86/include/asm/svm.h      |  9 +++++++--
 arch/x86/include/uapi/asm/svm.h |  3 +++
 arch/x86/kvm/svm/svm.h          | 17 +++++++++++++++--
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 772e60efe243..e322676039f4 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -156,6 +156,12 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 	u64 avic_physical_id;	/* Offset 0xf8 */
 	u8 reserved_7[8];
 	u64 vmsa_pa;		/* Used for an SEV-ES guest */
+	u8 reserved_8[720];
+	/*
+	 * Offset 0x3e0, 32 bytes reserved
+	 * for use by hypervisor/software.
+	 */
+	u8 reserved_sw[32];
 };
 
 
@@ -314,7 +320,7 @@ struct ghcb {
 
 
 #define EXPECTED_VMCB_SAVE_AREA_SIZE		1032
-#define EXPECTED_VMCB_CONTROL_AREA_SIZE		272
+#define EXPECTED_VMCB_CONTROL_AREA_SIZE		1024
 #define EXPECTED_GHCB_SIZE			PAGE_SIZE
 
 static inline void __unused_size_checks(void)
@@ -326,7 +332,6 @@ static inline void __unused_size_checks(void)
 
 struct vmcb {
 	struct vmcb_control_area control;
-	u8 reserved_control[1024 - sizeof(struct vmcb_control_area)];
 	struct vmcb_save_area save;
 } __packed;
 
diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
index 554f75fe013c..efa969325ede 100644
--- a/arch/x86/include/uapi/asm/svm.h
+++ b/arch/x86/include/uapi/asm/svm.h
@@ -110,6 +110,9 @@
 #define SVM_VMGEXIT_GET_AP_JUMP_TABLE		1
 #define SVM_VMGEXIT_UNSUPPORTED_EVENT		0x8000ffff
 
+/* Exit code reserved for hypervisor/software use */
+#define SVM_EXIT_SW				0xf0000000
+
 #define SVM_EXIT_ERR           -1
 
 #define SVM_EXIT_REASONS \
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 84b3133c2251..eb4b91832912 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -31,6 +31,11 @@
 extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
 extern bool npt_enabled;
 
+/*
+ * Clean bits in VMCB.
+ * VMCB_ALL_CLEAN_MASK might also need to
+ * be updated if this enum is modified.
+ */
 enum {
 	VMCB_INTERCEPTS, /* Intercept vectors, TSC offset,
 			    pause filter count */
@@ -48,9 +53,17 @@ enum {
 			  * AVIC PHYSICAL_TABLE pointer,
 			  * AVIC LOGICAL_TABLE pointer
 			  */
-	VMCB_DIRTY_MAX,
+	VMCB_SW = 31,    /* Reserved for hypervisor/software use */
 };
 
+#define VMCB_ALL_CLEAN_MASK (					\
+	(1U << VMCB_INTERCEPTS) | (1U << VMCB_PERM_MAP) |	\
+	(1U << VMCB_ASID) | (1U << VMCB_INTR) |			\
+	(1U << VMCB_NPT) | (1U << VMCB_CR) | (1U << VMCB_DR) |	\
+	(1U << VMCB_DT) | (1U << VMCB_SEG) | (1U << VMCB_CR2) |	\
+	(1U << VMCB_LBR) | (1U << VMCB_AVIC) |			\
+	(1U << VMCB_SW))
+
 /* TPR and CR2 are always written before VMRUN */
 #define VMCB_ALWAYS_DIRTY_MASK	((1U << VMCB_INTR) | (1U << VMCB_CR2))
 
@@ -237,7 +250,7 @@ static inline void vmcb_mark_all_dirty(struct vmcb *vmcb)
 
 static inline void vmcb_mark_all_clean(struct vmcb *vmcb)
 {
-	vmcb->control.clean = ((1 << VMCB_DIRTY_MAX) - 1)
+	vmcb->control.clean = VMCB_ALL_CLEAN_MASK
 			       & ~VMCB_ALWAYS_DIRTY_MASK;
 }
 
-- 
2.25.1