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Subject[RFC v2 10/32] x86/tdx: Wire up KVM hypercalls
Date
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

KVM hypercalls have to be wrapped into vendor-specific TDVMCALLs.

[Isaku: proposed KVM VENDOR string]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
arch/x86/include/asm/kvm_para.h | 21 +++++++++++++++
arch/x86/include/asm/tdx.h | 39 ++++++++++++++++++++++++++++
arch/x86/kernel/tdcall.S | 7 +++++
arch/x86/kernel/tdx-kvm.c | 45 +++++++++++++++++++++++++++++++++
arch/x86/kernel/tdx.c | 4 +++
5 files changed, 116 insertions(+)
create mode 100644 arch/x86/kernel/tdx-kvm.c

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 338119852512..2fa85481520b 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -6,6 +6,7 @@
#include <asm/alternative.h>
#include <linux/interrupt.h>
#include <uapi/asm/kvm_para.h>
+#include <asm/tdx.h>

extern void kvmclock_init(void);

@@ -34,6 +35,10 @@ static inline bool kvm_check_and_clear_guest_paused(void)
static inline long kvm_hypercall0(unsigned int nr)
{
long ret;
+
+ if (is_tdx_guest())
+ return tdx_kvm_hypercall0(nr);
+
asm volatile(KVM_HYPERCALL
: "=a"(ret)
: "a"(nr)
@@ -44,6 +49,10 @@ static inline long kvm_hypercall0(unsigned int nr)
static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
{
long ret;
+
+ if (is_tdx_guest())
+ return tdx_kvm_hypercall1(nr, p1);
+
asm volatile(KVM_HYPERCALL
: "=a"(ret)
: "a"(nr), "b"(p1)
@@ -55,6 +64,10 @@ static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
unsigned long p2)
{
long ret;
+
+ if (is_tdx_guest())
+ return tdx_kvm_hypercall2(nr, p1, p2);
+
asm volatile(KVM_HYPERCALL
: "=a"(ret)
: "a"(nr), "b"(p1), "c"(p2)
@@ -66,6 +79,10 @@ static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
unsigned long p2, unsigned long p3)
{
long ret;
+
+ if (is_tdx_guest())
+ return tdx_kvm_hypercall3(nr, p1, p2, p3);
+
asm volatile(KVM_HYPERCALL
: "=a"(ret)
: "a"(nr), "b"(p1), "c"(p2), "d"(p3)
@@ -78,6 +95,10 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
unsigned long p4)
{
long ret;
+
+ if (is_tdx_guest())
+ return tdx_kvm_hypercall4(nr, p1, p2, p3, p4);
+
asm volatile(KVM_HYPERCALL
: "=a"(ret)
: "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4)
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 1ca55d8e9963..e0b3ed9e262c 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -56,6 +56,16 @@ u64 __tdcall(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
/* Helper function used to request services from VMM */
u64 __tdvmcall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15,
struct tdvmcall_output *out);
+u64 __tdvmcall_vendor_kvm(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15,
+ struct tdvmcall_output *out);
+
+long tdx_kvm_hypercall0(unsigned int nr);
+long tdx_kvm_hypercall1(unsigned int nr, unsigned long p1);
+long tdx_kvm_hypercall2(unsigned int nr, unsigned long p1, unsigned long p2);
+long tdx_kvm_hypercall3(unsigned int nr, unsigned long p1, unsigned long p2,
+ unsigned long p3);
+long tdx_kvm_hypercall4(unsigned int nr, unsigned long p1, unsigned long p2,
+ unsigned long p3, unsigned long p4);

#else // !CONFIG_INTEL_TDX_GUEST

@@ -66,6 +76,35 @@ static inline bool is_tdx_guest(void)

static inline void tdx_early_init(void) { };

+static inline long tdx_kvm_hypercall0(unsigned int nr)
+{
+ return -ENODEV;
+}
+
+static inline long tdx_kvm_hypercall1(unsigned int nr, unsigned long p1)
+{
+ return -ENODEV;
+}
+
+static inline long tdx_kvm_hypercall2(unsigned int nr, unsigned long p1,
+ unsigned long p2)
+{
+ return -ENODEV;
+}
+
+static inline long tdx_kvm_hypercall3(unsigned int nr, unsigned long p1,
+ unsigned long p2, unsigned long p3)
+{
+ return -ENODEV;
+}
+
+static inline long tdx_kvm_hypercall4(unsigned int nr, unsigned long p1,
+ unsigned long p2, unsigned long p3,
+ unsigned long p4)
+{
+ return -ENODEV;
+}
+
#endif /* CONFIG_INTEL_TDX_GUEST */

#endif /* _ASM_X86_TDX_H */
diff --git a/arch/x86/kernel/tdcall.S b/arch/x86/kernel/tdcall.S
index 81af70c2acbd..964bfd7fc682 100644
--- a/arch/x86/kernel/tdcall.S
+++ b/arch/x86/kernel/tdcall.S
@@ -11,6 +11,7 @@
* refer to TDX GHCI specification).
*/
#define TDVMCALL_EXPOSE_REGS_MASK 0xfc00
+#define TDVMCALL_VENDOR_KVM 0x4d564b2e584454 /* "TDX.KVM" */

/*
* TDX guests use the TDCALL instruction to make
@@ -198,3 +199,9 @@ SYM_FUNC_START(__tdvmcall)
call do_tdvmcall
retq
SYM_FUNC_END(__tdvmcall)
+
+SYM_FUNC_START(__tdvmcall_vendor_kvm)
+ movq $TDVMCALL_VENDOR_KVM, %r10
+ call do_tdvmcall
+ retq
+SYM_FUNC_END(__tdvmcall_vendor_kvm)
diff --git a/arch/x86/kernel/tdx-kvm.c b/arch/x86/kernel/tdx-kvm.c
new file mode 100644
index 000000000000..c4264e926712
--- /dev/null
+++ b/arch/x86/kernel/tdx-kvm.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+
+static long tdvmcall_vendor(unsigned int fn, unsigned long r12,
+ unsigned long r13, unsigned long r14,
+ unsigned long r15)
+{
+ return __tdvmcall_vendor_kvm(fn, r12, r13, r14, r15, NULL);
+}
+
+/* Used by kvm_hypercall0() to trigger hypercall in TDX guest */
+long tdx_kvm_hypercall0(unsigned int nr)
+{
+ return tdvmcall_vendor(nr, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL_GPL(tdx_kvm_hypercall0);
+
+/* Used by kvm_hypercall1() to trigger hypercall in TDX guest */
+long tdx_kvm_hypercall1(unsigned int nr, unsigned long p1)
+{
+ return tdvmcall_vendor(nr, p1, 0, 0, 0);
+}
+EXPORT_SYMBOL_GPL(tdx_kvm_hypercall1);
+
+/* Used by kvm_hypercall2() to trigger hypercall in TDX guest */
+long tdx_kvm_hypercall2(unsigned int nr, unsigned long p1, unsigned long p2)
+{
+ return tdvmcall_vendor(nr, p1, p2, 0, 0);
+}
+EXPORT_SYMBOL_GPL(tdx_kvm_hypercall2);
+
+/* Used by kvm_hypercall3() to trigger hypercall in TDX guest */
+long tdx_kvm_hypercall3(unsigned int nr, unsigned long p1, unsigned long p2,
+ unsigned long p3)
+{
+ return tdvmcall_vendor(nr, p1, p2, p3, 0);
+}
+EXPORT_SYMBOL_GPL(tdx_kvm_hypercall3);
+
+/* Used by kvm_hypercall4() to trigger hypercall in TDX guest */
+long tdx_kvm_hypercall4(unsigned int nr, unsigned long p1, unsigned long p2,
+ unsigned long p3, unsigned long p4)
+{
+ return tdvmcall_vendor(nr, p1, p2, p3, p4);
+}
+EXPORT_SYMBOL_GPL(tdx_kvm_hypercall4);
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index 5169f72b6b3f..721c213d807d 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -8,6 +8,10 @@

#include <linux/cpu.h>

+#ifdef CONFIG_KVM_GUEST
+#include "tdx-kvm.c"
+#endif
+
static struct {
unsigned int gpa_width;
unsigned long attributes;
--
2.25.1
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