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Subject[PATCH v4 4/7] KVM: SVM: Software reserved fields
Date
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@linux.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 1c561945b426..8dac318bd6f9 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];
};


@@ -312,7 +318,7 @@ 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)
@@ -324,7 +330,6 @@ 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 39e071fdab0c..4e073b88c8cb 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -33,6 +33,11 @@ static const u32 host_save_user_msrs[] = {
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 */
@@ -50,9 +55,17 @@ 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))

@@ -230,7 +243,7 @@ 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
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