[RFC 11/16] KVM: selftests: add library for handling SEV-ES-related exits

[Michael Roth <michael.roth@amd.com>]

Add (or copy from kernel) routines related to handling #VC exceptions
(only for cpuid currently) or issuing vmgexits. These will be used
mostly by guest code.

Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 tools/testing/selftests/kvm/Makefile          |   2 +-
 .../kvm/include/x86_64/sev_exitlib.h          |  14 +
 .../selftests/kvm/include/x86_64/svm.h        |  35 +++
 .../selftests/kvm/include/x86_64/svm_util.h   |   1 +
 .../selftests/kvm/lib/x86_64/sev_exitlib.c    | 249 ++++++++++++++++++
 5 files changed, 300 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h
 create mode 100644 tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index aa8901bdbd22..7b3261cc60a3 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -35,7 +35,7 @@ endif
 
 LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/rbtree.c lib/sparsebit.c lib/test_util.c lib/guest_modes.c lib/perf_test_util.c
 LIBKVM_x86_64 = lib/x86_64/apic.c lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
-LIBKVM_x86_64 += lib/x86_64/sev.c
+LIBKVM_x86_64 += lib/x86_64/sev.c lib/x86_64/sev_exitlib.c
 LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S
 LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c
 
diff --git a/tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h b/tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h
new file mode 100644
index 000000000000..4b67b4004dfa
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * VC/vmgexit/GHCB-related helpers for SEV-ES/SEV-SNP guests.
+ *
+ * Copyright (C) 2021 Advanced Micro Devices
+ */
+
+#ifndef SELFTEST_KVM_SEV_EXITLIB_H
+#define SELFTEST_KVM_SEV_EXITLIB_H
+
+int sev_es_handle_vc(void *ghcb, u64 ghcb_gpa, struct ex_regs *regs);
+void sev_es_terminate(int reason);
+
+#endif /* SELFTEST_KVM_SEV_EXITLIB_H */
diff --git a/tools/testing/selftests/kvm/include/x86_64/svm.h b/tools/testing/selftests/kvm/include/x86_64/svm.h
index f4ea2355dbc2..d633caea4b7d 100644
--- a/tools/testing/selftests/kvm/include/x86_64/svm.h
+++ b/tools/testing/selftests/kvm/include/x86_64/svm.h
@@ -204,6 +204,41 @@ struct __attribute__ ((__packed__)) vmcb_save_area {
 	u64 br_to;
 	u64 last_excp_from;
 	u64 last_excp_to;
+
+	/*
+	 * The following part of the save area is valid only for
+	 * SEV-ES guests when referenced through the GHCB or for
+	 * saving to the host save area.
+	 */
+	u8 reserved_7[80];
+	u32 pkru;
+	u8 reserved_7a[20];
+	u64 reserved_8;		/* rax already available at 0x01f8 */
+	u64 rcx;
+	u64 rdx;
+	u64 rbx;
+	u64 reserved_9;		/* rsp already available at 0x01d8 */
+	u64 rbp;
+	u64 rsi;
+	u64 rdi;
+	u64 r8;
+	u64 r9;
+	u64 r10;
+	u64 r11;
+	u64 r12;
+	u64 r13;
+	u64 r14;
+	u64 r15;
+	u8 reserved_10[16];
+	u64 sw_exit_code;
+	u64 sw_exit_info_1;
+	u64 sw_exit_info_2;
+	u64 sw_scratch;
+	u64 sev_features;
+	u8 reserved_11[48];
+	u64 xcr0;
+	u8 valid_bitmap[16];
+	u64 x87_state_gpa;
 };
 
 struct __attribute__ ((__packed__)) vmcb {
diff --git a/tools/testing/selftests/kvm/include/x86_64/svm_util.h b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
index b7531c83b8ae..4319bb6f4691 100644
--- a/tools/testing/selftests/kvm/include/x86_64/svm_util.h
+++ b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
@@ -16,6 +16,7 @@
 #define CPUID_SVM_BIT		2
 #define CPUID_SVM		BIT_ULL(CPUID_SVM_BIT)
 
+#define SVM_EXIT_CPUID		0x072
 #define SVM_EXIT_VMMCALL	0x081
 
 struct svm_test_data {
diff --git a/tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c b/tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c
new file mode 100644
index 000000000000..b3f7b0297e5b
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * GHCB/#VC/instruction helpers for use with SEV-ES/SEV-SNP guests.
+ *
+ * Partially copied from arch/x86/kernel/sev*.c
+ *
+ * Copyright (C) 2021 Advanced Micro Devices
+ */
+
+#include <linux/bitops.h>
+#include <kvm_util.h>			/* needed by kvm_util_internal.h */
+#include "../kvm_util_internal.h"	/* needed by processor.h */
+#include "processor.h"			/* for struct ex_regs */
+#include "svm_util.h"			/* for additional SVM_EXIT_* definitions */
+#include "svm.h"			/* for VMCB/VMSA layout */
+#include "sev_exitlib.h"
+
+#define PAGE_SHIFT 12
+
+#define MSR_SEV_ES_GHCB 0xc0010130
+
+#define VMGEXIT() { asm volatile("rep; vmmcall\n\r"); }
+
+#define GHCB_PROTOCOL_MAX	1
+#define GHCB_DEFAULT_USAGE	0
+
+/* Guest-requested termination codes */
+#define GHCB_TERMINATE 0x100UL
+#define GHCB_TERMINATE_REASON(reason_set, reason_val)	\
+	(((((u64)reason_set) &  0x7) << 12) |			\
+	 ((((u64)reason_val) & 0xff) << 16))
+
+#define GHCB_TERMINATE_REASON_UNSPEC 0
+
+/* GHCB MSR protocol for CPUID */
+#define GHCB_CPUID_REQ_EAX 0
+#define GHCB_CPUID_REQ_EBX 1
+#define GHCB_CPUID_REQ_ECX 2
+#define GHCB_CPUID_REQ_EDX 3
+#define GHCB_CPUID_REQ_CODE 0x4UL
+#define GHCB_CPUID_REQ(fn, reg) \
+	(GHCB_CPUID_REQ_CODE | (((uint64_t)reg & 3) << 30) | (((uint64_t)fn) << 32))
+#define GHCB_CPUID_RESP_CODE 0x5UL
+#define GHCB_CPUID_RESP(resp) ((resp) & 0xfff)
+
+/* GHCB MSR protocol for GHCB registration */
+#define GHCB_REG_GPA_REQ_CODE 0x12UL
+#define GHCB_REG_GPA_REQ(gfn) \
+	(((unsigned long)((gfn) & GENMASK_ULL(51, 0)) << 12) | GHCB_REG_GPA_REQ_CODE)
+#define GHCB_REG_GPA_RESP_CODE 0x13UL
+#define GHCB_REG_GPA_RESP(resp) ((resp) & GENMASK_ULL(11, 0))
+#define GHCB_REG_GPA_RESP_VAL(resp) ((resp) >> 12)
+
+/* GHCB format/accessors */
+
+struct ghcb {
+	struct vmcb_save_area save;
+	u8 reserved_save[2048 - sizeof(struct vmcb_save_area)];
+	u8 shared_buffer[2032];
+	u8 reserved_1[10];
+	u16 protocol_version;
+	u32 ghcb_usage;
+};
+
+#define GHCB_BITMAP_IDX(field)							\
+	(offsetof(struct vmcb_save_area, field) / sizeof(u64))
+
+#define DEFINE_GHCB_ACCESSORS(field)						\
+	static inline bool ghcb_##field##_is_valid(const struct ghcb *ghcb)	\
+	{									\
+		return test_bit(GHCB_BITMAP_IDX(field),				\
+				(unsigned long *)&ghcb->save.valid_bitmap);	\
+	}									\
+										\
+	static inline u64 ghcb_get_##field(struct ghcb *ghcb)			\
+	{									\
+		return ghcb->save.field;					\
+	}									\
+										\
+	static inline u64 ghcb_get_##field##_if_valid(struct ghcb *ghcb)	\
+	{									\
+		return ghcb_##field##_is_valid(ghcb) ? ghcb->save.field : 0;	\
+	}									\
+										\
+	static inline void ghcb_set_##field(struct ghcb *ghcb, u64 value)	\
+	{									\
+		__set_bit(GHCB_BITMAP_IDX(field),				\
+			  (unsigned long *)&ghcb->save.valid_bitmap);		\
+		ghcb->save.field = value;					\
+	}
+
+DEFINE_GHCB_ACCESSORS(cpl)
+DEFINE_GHCB_ACCESSORS(rip)
+DEFINE_GHCB_ACCESSORS(rsp)
+DEFINE_GHCB_ACCESSORS(rax)
+DEFINE_GHCB_ACCESSORS(rcx)
+DEFINE_GHCB_ACCESSORS(rdx)
+DEFINE_GHCB_ACCESSORS(rbx)
+DEFINE_GHCB_ACCESSORS(rbp)
+DEFINE_GHCB_ACCESSORS(rsi)
+DEFINE_GHCB_ACCESSORS(rdi)
+DEFINE_GHCB_ACCESSORS(r8)
+DEFINE_GHCB_ACCESSORS(r9)
+DEFINE_GHCB_ACCESSORS(r10)
+DEFINE_GHCB_ACCESSORS(r11)
+DEFINE_GHCB_ACCESSORS(r12)
+DEFINE_GHCB_ACCESSORS(r13)
+DEFINE_GHCB_ACCESSORS(r14)
+DEFINE_GHCB_ACCESSORS(r15)
+DEFINE_GHCB_ACCESSORS(sw_exit_code)
+DEFINE_GHCB_ACCESSORS(sw_exit_info_1)
+DEFINE_GHCB_ACCESSORS(sw_exit_info_2)
+DEFINE_GHCB_ACCESSORS(sw_scratch)
+DEFINE_GHCB_ACCESSORS(xcr0)
+
+static uint64_t sev_es_rdmsr_ghcb(void)
+{
+	uint64_t lo, hi;
+
+	asm volatile("rdmsr"
+		     : "=a" (lo), "=d" (hi)
+		     : "c" (MSR_SEV_ES_GHCB));
+
+	return ((hi << 32) | lo);
+}
+
+static void sev_es_wrmsr_ghcb(uint64_t val)
+{
+	uint64_t lo, hi;
+
+	lo = val & 0xFFFFFFFF;
+	hi = val >> 32;
+
+	asm volatile("wrmsr"
+		     :: "c" (MSR_SEV_ES_GHCB), "a" (lo), "d" (hi)
+		     : "memory");
+}
+
+void sev_es_terminate(int reason)
+{
+	uint64_t val = GHCB_TERMINATE;
+
+	val |= GHCB_TERMINATE_REASON(2, reason);
+
+	sev_es_wrmsr_ghcb(val);
+	VMGEXIT();
+
+	while (true)
+		asm volatile("hlt" : : : "memory");
+}
+
+static int sev_es_ghcb_hv_call(struct ghcb *ghcb, u64 ghcb_gpa, u64 exit_code)
+{
+	ghcb->protocol_version = GHCB_PROTOCOL_MAX;
+	ghcb->ghcb_usage = GHCB_DEFAULT_USAGE;
+
+	ghcb_set_sw_exit_code(ghcb, exit_code);
+	ghcb_set_sw_exit_info_1(ghcb, 0);
+	ghcb_set_sw_exit_info_2(ghcb, 0);
+
+	sev_es_wrmsr_ghcb(ghcb_gpa);
+
+	VMGEXIT();
+
+	/* Only #VC exceptions are currently handled. */
+	if ((ghcb->save.sw_exit_info_1 & 0xffffffff) == 1)
+		sev_es_terminate(GHCB_TERMINATE_REASON_UNSPEC);
+
+	return 0;
+}
+
+static int handle_vc_cpuid(struct ghcb *ghcb, u64 ghcb_gpa, struct ex_regs *regs)
+{
+	int ret;
+
+	ghcb_set_rax(ghcb, regs->rax);
+	ghcb_set_rcx(ghcb, regs->rcx);
+
+	/* ignore additional XSAVE states for now */
+	ghcb_set_xcr0(ghcb, 1);
+
+	ret = sev_es_ghcb_hv_call(ghcb, ghcb_gpa, SVM_EXIT_CPUID);
+	if (ret)
+		return ret;
+
+	if (!(ghcb_rax_is_valid(ghcb) &&
+	      ghcb_rbx_is_valid(ghcb) &&
+	      ghcb_rcx_is_valid(ghcb) &&
+	      ghcb_rdx_is_valid(ghcb)))
+		return 1;
+
+	regs->rax = ghcb->save.rax;
+	regs->rbx = ghcb->save.rbx;
+	regs->rcx = ghcb->save.rcx;
+	regs->rdx = ghcb->save.rdx;
+
+	regs->rip += 2;
+
+	return 0;
+}
+
+static int handle_msr_vc_cpuid(struct ex_regs *regs)
+{
+	uint32_t fn = regs->rax & 0xFFFFFFFF;
+	uint64_t resp;
+
+	sev_es_wrmsr_ghcb(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EAX));
+	VMGEXIT();
+	resp = sev_es_rdmsr_ghcb();
+	if (GHCB_CPUID_RESP(resp) != GHCB_CPUID_RESP_CODE)
+		return 1;
+	regs->rax = resp >> 32;
+
+	sev_es_wrmsr_ghcb(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EBX));
+	VMGEXIT();
+	resp = sev_es_rdmsr_ghcb();
+	if (GHCB_CPUID_RESP(resp) != GHCB_CPUID_RESP_CODE)
+		return 1;
+	regs->rbx = resp >> 32;
+
+	sev_es_wrmsr_ghcb(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_ECX));
+	VMGEXIT();
+	resp = sev_es_rdmsr_ghcb();
+	if (GHCB_CPUID_RESP(resp) != GHCB_CPUID_RESP_CODE)
+		return 1;
+	regs->rcx = resp >> 32;
+
+	sev_es_wrmsr_ghcb(GHCB_CPUID_REQ(fn, GHCB_CPUID_REQ_EDX));
+	VMGEXIT();
+	resp = sev_es_rdmsr_ghcb();
+	if (GHCB_CPUID_RESP(resp) != GHCB_CPUID_RESP_CODE)
+		return 1;
+	regs->rdx = resp >> 32;
+
+	regs->rip += 2;
+
+	return 0;
+}
+
+int sev_es_handle_vc(void *ghcb, u64 ghcb_gpa, struct ex_regs *regs)
+{
+	if (regs->error_code != SVM_EXIT_CPUID)
+		return 1;
+
+	if (!ghcb)
+		return handle_msr_vc_cpuid(regs);
+
+	return handle_vc_cpuid(ghcb, ghcb_gpa, regs);
+}
-- 
2.25.1