KVM: x86: smm: add structs for KVM's smram layout

Add structs that will be used to define and read/write the KVM's
SMRAM layout, instead of reading/writing to raw offsets.

Also document the differences between KVM's SMRAM layout and SMRAM
layout that is used by real Intel/AMD cpus.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20221025124741.228045-17-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 231 insertions, 0 deletions

diff --git a/arch/x86/kvm/smm.c b/arch/x86/kvm/smm.c
index 2d5bb2af70e4..2e6ec79a581e 100644
--- a/arch/x86/kvm/smm.c
+++ b/arch/x86/kvm/smm.c
@@ -8,6 +8,102 @@
 #include "cpuid.h"
 #include "trace.h"
 
+#define CHECK_SMRAM32_OFFSET(field, offset) \
+	ASSERT_STRUCT_OFFSET(struct kvm_smram_state_32, field, offset - 0xFE00)
+
+#define CHECK_SMRAM64_OFFSET(field, offset) \
+	ASSERT_STRUCT_OFFSET(struct kvm_smram_state_64, field, offset - 0xFE00)
+
+static void check_smram_offsets(void)
+{
+	/* 32 bit SMRAM image */
+	CHECK_SMRAM32_OFFSET(reserved1,			0xFE00);
+	CHECK_SMRAM32_OFFSET(smbase,			0xFEF8);
+	CHECK_SMRAM32_OFFSET(smm_revision,		0xFEFC);
+	CHECK_SMRAM32_OFFSET(io_inst_restart,		0xFF00);
+	CHECK_SMRAM32_OFFSET(auto_hlt_restart,		0xFF02);
+	CHECK_SMRAM32_OFFSET(io_restart_rdi,		0xFF04);
+	CHECK_SMRAM32_OFFSET(io_restart_rcx,		0xFF08);
+	CHECK_SMRAM32_OFFSET(io_restart_rsi,		0xFF0C);
+	CHECK_SMRAM32_OFFSET(io_restart_rip,		0xFF10);
+	CHECK_SMRAM32_OFFSET(cr4,			0xFF14);
+	CHECK_SMRAM32_OFFSET(reserved3,			0xFF18);
+	CHECK_SMRAM32_OFFSET(ds,			0xFF2C);
+	CHECK_SMRAM32_OFFSET(fs,			0xFF38);
+	CHECK_SMRAM32_OFFSET(gs,			0xFF44);
+	CHECK_SMRAM32_OFFSET(idtr,			0xFF50);
+	CHECK_SMRAM32_OFFSET(tr,			0xFF5C);
+	CHECK_SMRAM32_OFFSET(gdtr,			0xFF6C);
+	CHECK_SMRAM32_OFFSET(ldtr,			0xFF78);
+	CHECK_SMRAM32_OFFSET(es,			0xFF84);
+	CHECK_SMRAM32_OFFSET(cs,			0xFF90);
+	CHECK_SMRAM32_OFFSET(ss,			0xFF9C);
+	CHECK_SMRAM32_OFFSET(es_sel,			0xFFA8);
+	CHECK_SMRAM32_OFFSET(cs_sel,			0xFFAC);
+	CHECK_SMRAM32_OFFSET(ss_sel,			0xFFB0);
+	CHECK_SMRAM32_OFFSET(ds_sel,			0xFFB4);
+	CHECK_SMRAM32_OFFSET(fs_sel,			0xFFB8);
+	CHECK_SMRAM32_OFFSET(gs_sel,			0xFFBC);
+	CHECK_SMRAM32_OFFSET(ldtr_sel,			0xFFC0);
+	CHECK_SMRAM32_OFFSET(tr_sel,			0xFFC4);
+	CHECK_SMRAM32_OFFSET(dr7,			0xFFC8);
+	CHECK_SMRAM32_OFFSET(dr6,			0xFFCC);
+	CHECK_SMRAM32_OFFSET(gprs,			0xFFD0);
+	CHECK_SMRAM32_OFFSET(eip,			0xFFF0);
+	CHECK_SMRAM32_OFFSET(eflags,			0xFFF4);
+	CHECK_SMRAM32_OFFSET(cr3,			0xFFF8);
+	CHECK_SMRAM32_OFFSET(cr0,			0xFFFC);
+
+	/* 64 bit SMRAM image */
+	CHECK_SMRAM64_OFFSET(es,			0xFE00);
+	CHECK_SMRAM64_OFFSET(cs,			0xFE10);
+	CHECK_SMRAM64_OFFSET(ss,			0xFE20);
+	CHECK_SMRAM64_OFFSET(ds,			0xFE30);
+	CHECK_SMRAM64_OFFSET(fs,			0xFE40);
+	CHECK_SMRAM64_OFFSET(gs,			0xFE50);
+	CHECK_SMRAM64_OFFSET(gdtr,			0xFE60);
+	CHECK_SMRAM64_OFFSET(ldtr,			0xFE70);
+	CHECK_SMRAM64_OFFSET(idtr,			0xFE80);
+	CHECK_SMRAM64_OFFSET(tr,			0xFE90);
+	CHECK_SMRAM64_OFFSET(io_restart_rip,		0xFEA0);
+	CHECK_SMRAM64_OFFSET(io_restart_rcx,		0xFEA8);
+	CHECK_SMRAM64_OFFSET(io_restart_rsi,		0xFEB0);
+	CHECK_SMRAM64_OFFSET(io_restart_rdi,		0xFEB8);
+	CHECK_SMRAM64_OFFSET(io_restart_dword,		0xFEC0);
+	CHECK_SMRAM64_OFFSET(reserved1,			0xFEC4);
+	CHECK_SMRAM64_OFFSET(io_inst_restart,		0xFEC8);
+	CHECK_SMRAM64_OFFSET(auto_hlt_restart,		0xFEC9);
+	CHECK_SMRAM64_OFFSET(reserved2,			0xFECA);
+	CHECK_SMRAM64_OFFSET(efer,			0xFED0);
+	CHECK_SMRAM64_OFFSET(svm_guest_flag,		0xFED8);
+	CHECK_SMRAM64_OFFSET(svm_guest_vmcb_gpa,	0xFEE0);
+	CHECK_SMRAM64_OFFSET(svm_guest_virtual_int,	0xFEE8);
+	CHECK_SMRAM64_OFFSET(reserved3,			0xFEF0);
+	CHECK_SMRAM64_OFFSET(smm_revison,		0xFEFC);
+	CHECK_SMRAM64_OFFSET(smbase,			0xFF00);
+	CHECK_SMRAM64_OFFSET(reserved4,			0xFF04);
+	CHECK_SMRAM64_OFFSET(ssp,			0xFF18);
+	CHECK_SMRAM64_OFFSET(svm_guest_pat,		0xFF20);
+	CHECK_SMRAM64_OFFSET(svm_host_efer,		0xFF28);
+	CHECK_SMRAM64_OFFSET(svm_host_cr4,		0xFF30);
+	CHECK_SMRAM64_OFFSET(svm_host_cr3,		0xFF38);
+	CHECK_SMRAM64_OFFSET(svm_host_cr0,		0xFF40);
+	CHECK_SMRAM64_OFFSET(cr4,			0xFF48);
+	CHECK_SMRAM64_OFFSET(cr3,			0xFF50);
+	CHECK_SMRAM64_OFFSET(cr0,			0xFF58);
+	CHECK_SMRAM64_OFFSET(dr7,			0xFF60);
+	CHECK_SMRAM64_OFFSET(dr6,			0xFF68);
+	CHECK_SMRAM64_OFFSET(rflags,			0xFF70);
+	CHECK_SMRAM64_OFFSET(rip,			0xFF78);
+	CHECK_SMRAM64_OFFSET(gprs,			0xFF80);
+
+	BUILD_BUG_ON(sizeof(union kvm_smram) != 512);
+}
+
+#undef CHECK_SMRAM64_OFFSET
+#undef CHECK_SMRAM32_OFFSET
+
+
 void kvm_smm_changed(struct kvm_vcpu *vcpu, bool entering_smm)
 {
 	BUILD_BUG_ON(HF_SMM_MASK != X86EMUL_SMM_MASK);
@@ -201,6 +297,8 @@ void enter_smm(struct kvm_vcpu *vcpu)
 	unsigned long cr0;
 	char buf[512];
 
+	check_smram_offsets();
+
 	memset(buf, 0, 512);
 #ifdef CONFIG_X86_64
 	if (guest_cpuid_has(vcpu, X86_FEATURE_LM))
diff --git a/arch/x86/kvm/smm.h b/arch/x86/kvm/smm.h
index 53c81394ebdb..b66da263ec82 100644
--- a/arch/x86/kvm/smm.h
+++ b/arch/x86/kvm/smm.h
@@ -2,6 +2,8 @@
 #ifndef ASM_KVM_SMM_H
 #define ASM_KVM_SMM_H
 
+#include <linux/build_bug.h>
+
 #define GET_SMSTATE(type, buf, offset)		\
 	(*(type *)((buf) + (offset) - 0x7e00))
 
@@ -9,6 +11,137 @@
 	*(type *)((buf) + (offset) - 0x7e00) = val
 
 #ifdef CONFIG_KVM_SMM
+
+
+/*
+ * 32 bit KVM's emulated SMM layout. Based on Intel P6 layout
+ * (https://www.sandpile.org/x86/smm.htm).
+ */
+
+struct kvm_smm_seg_state_32 {
+	u32 flags;
+	u32 limit;
+	u32 base;
+} __packed;
+
+struct kvm_smram_state_32 {
+	u32 reserved1[62];
+	u32 smbase;
+	u32 smm_revision;
+	u16 io_inst_restart;
+	u16 auto_hlt_restart;
+	u32 io_restart_rdi;
+	u32 io_restart_rcx;
+	u32 io_restart_rsi;
+	u32 io_restart_rip;
+	u32 cr4;
+
+	/* A20M#, CPL, shutdown and other reserved/undocumented fields */
+	u32 reserved3[5];
+
+	struct kvm_smm_seg_state_32 ds;
+	struct kvm_smm_seg_state_32 fs;
+	struct kvm_smm_seg_state_32 gs;
+	struct kvm_smm_seg_state_32 idtr; /* IDTR has only base and limit */
+	struct kvm_smm_seg_state_32 tr;
+	u32 reserved;
+	struct kvm_smm_seg_state_32 gdtr; /* GDTR has only base and limit */
+	struct kvm_smm_seg_state_32 ldtr;
+	struct kvm_smm_seg_state_32 es;
+	struct kvm_smm_seg_state_32 cs;
+	struct kvm_smm_seg_state_32 ss;
+
+	u32 es_sel;
+	u32 cs_sel;
+	u32 ss_sel;
+	u32 ds_sel;
+	u32 fs_sel;
+	u32 gs_sel;
+	u32 ldtr_sel;
+	u32 tr_sel;
+
+	u32 dr7;
+	u32 dr6;
+	u32 gprs[8]; /* GPRS in the "natural" X86 order (EAX/ECX/EDX.../EDI) */
+	u32 eip;
+	u32 eflags;
+	u32 cr3;
+	u32 cr0;
+} __packed;
+
+
+/* 64 bit KVM's emulated SMM layout. Based on AMD64 layout */
+
+struct kvm_smm_seg_state_64 {
+	u16 selector;
+	u16 attributes;
+	u32 limit;
+	u64 base;
+};
+
+struct kvm_smram_state_64 {
+
+	struct kvm_smm_seg_state_64 es;
+	struct kvm_smm_seg_state_64 cs;
+	struct kvm_smm_seg_state_64 ss;
+	struct kvm_smm_seg_state_64 ds;
+	struct kvm_smm_seg_state_64 fs;
+	struct kvm_smm_seg_state_64 gs;
+	struct kvm_smm_seg_state_64 gdtr; /* GDTR has only base and limit*/
+	struct kvm_smm_seg_state_64 ldtr;
+	struct kvm_smm_seg_state_64 idtr; /* IDTR has only base and limit*/
+	struct kvm_smm_seg_state_64 tr;
+
+	/* I/O restart and auto halt restart are not implemented by KVM */
+	u64 io_restart_rip;
+	u64 io_restart_rcx;
+	u64 io_restart_rsi;
+	u64 io_restart_rdi;
+	u32 io_restart_dword;
+	u32 reserved1;
+	u8 io_inst_restart;
+	u8 auto_hlt_restart;
+	u8 reserved2[6];
+
+	u64 efer;
+
+	/*
+	 * Two fields below are implemented on AMD only, to store
+	 * SVM guest vmcb address if the #SMI was received while in the guest mode.
+	 */
+	u64 svm_guest_flag;
+	u64 svm_guest_vmcb_gpa;
+	u64 svm_guest_virtual_int; /* unknown purpose, not implemented */
+
+	u32 reserved3[3];
+	u32 smm_revison;
+	u32 smbase;
+	u32 reserved4[5];
+
+	/* ssp and svm_* fields below are not implemented by KVM */
+	u64 ssp;
+	u64 svm_guest_pat;
+	u64 svm_host_efer;
+	u64 svm_host_cr4;
+	u64 svm_host_cr3;
+	u64 svm_host_cr0;
+
+	u64 cr4;
+	u64 cr3;
+	u64 cr0;
+	u64 dr7;
+	u64 dr6;
+	u64 rflags;
+	u64 rip;
+	u64 gprs[16]; /* GPRS in a reversed "natural" X86 order (R15/R14/../RCX/RAX.) */
+};
+
+union kvm_smram {
+	struct kvm_smram_state_64 smram64;
+	struct kvm_smram_state_32 smram32;
+	u8 bytes[512];
+};
+
 static inline int kvm_inject_smi(struct kvm_vcpu *vcpu)
 {
 	kvm_make_request(KVM_REQ_SMI, vcpu);