x86/vmware: Add a header file for hypercall definitions

The new header is intended to be used by drivers using the backdoor.
Follow the KVM example using alternatives self-patching to choose
between vmcall, vmmcall and io instructions.

Also define two new CPU feature flags to indicate hypervisor support
for vmcall- and vmmcall instructions. The new XF86_FEATURE_VMW_VMMCALL
flag is needed because using XF86_FEATURE_VMMCALL might break QEMU/KVM
setups using the vmmouse driver. They rely on XF86_FEATURE_VMMCALL
on AMD to get the kvm_hypercall() right. But they do not yet implement
vmmcall for the VMware hypercall used by the vmmouse driver.

 [ bp: reflow hypercall %edx usage explanation comment. ]

Signed-off-by: Thomas Hellstrom <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Doug Covelli <[email protected]>
Cc: Aaron Lewis <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: [email protected]
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Nicolas Ferre <[email protected]>
Cc: Robert Hoo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: <[email protected]>
Cc: x86-ml <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

Author: thomashvmw

MAINTAINERS

@@ -17206,6 +17206,7 @@ M:	"VMware, Inc." <[email protected]>
 L:	[email protected]
 S:	Supported
 F:	arch/x86/kernel/cpu/vmware.c
+F:	arch/x86/include/asm/vmware.h
 
 VMWARE PVRDMA DRIVER
 M:	Adit Ranadive <[email protected]>

arch/x86/include/asm/cpufeatures.h

@@ -232,6 +232,8 @@
 #define X86_FEATURE_VMMCALL		( 8*32+15) /* Prefer VMMCALL to VMCALL */
 #define X86_FEATURE_XENPV		( 8*32+16) /* "" Xen paravirtual guest */
 #define X86_FEATURE_EPT_AD		( 8*32+17) /* Intel Extended Page Table access-dirty bit */
+#define X86_FEATURE_VMCALL		( 8*32+18) /* "" Hypervisor supports the VMCALL instruction */
+#define X86_FEATURE_VMW_VMMCALL		( 8*32+19) /* "" VMware prefers VMMCALL hypercall instruction */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
 #define X86_FEATURE_FSGSBASE		( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/

arch/x86/include/asm/vmware.h

@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 or MIT */
+#ifndef _ASM_X86_VMWARE_H
+#define _ASM_X86_VMWARE_H
+
+#include <asm/cpufeatures.h>
+#include <asm/alternative.h>
+
+/*
+ * The hypercall definitions differ in the low word of the %edx argument
+ * in the following way: the old port base interface uses the port
+ * number to distinguish between high- and low bandwidth versions.
+ *
+ * The new vmcall interface instead uses a set of flags to select
+ * bandwidth mode and transfer direction. The flags should be loaded
+ * into %dx by any user and are automatically replaced by the port
+ * number if the VMWARE_HYPERVISOR_PORT method is used.
+ *
+ * In short, new driver code should strictly use the new definition of
+ * %dx content.
+ */
+
+/* Old port-based version */
+#define VMWARE_HYPERVISOR_PORT    "0x5658"
+#define VMWARE_HYPERVISOR_PORT_HB "0x5659"
+
+/* Current vmcall / vmmcall version */
+#define VMWARE_HYPERVISOR_HB   BIT(0)
+#define VMWARE_HYPERVISOR_OUT  BIT(1)
+
+/* The low bandwidth call. The low word of edx is presumed clear. */
+#define VMWARE_HYPERCALL						\
+	ALTERNATIVE_2("movw $" VMWARE_HYPERVISOR_PORT ", %%dx; inl (%%dx)", \
+		      "vmcall", X86_FEATURE_VMCALL,			\
+		      "vmmcall", X86_FEATURE_VMW_VMMCALL)
+
+/*
+ * The high bandwidth out call. The low word of edx is presumed to have the
+ * HB and OUT bits set.
+ */
+#define VMWARE_HYPERCALL_HB_OUT						\
+	ALTERNATIVE_2("movw $" VMWARE_HYPERVISOR_PORT_HB ", %%dx; rep outsb", \
+		      "vmcall", X86_FEATURE_VMCALL,			\
+		      "vmmcall", X86_FEATURE_VMW_VMMCALL)
+
+/*
+ * The high bandwidth in call. The low word of edx is presumed to have the
+ * HB bit set.
+ */
+#define VMWARE_HYPERCALL_HB_IN						\
+	ALTERNATIVE_2("movw $" VMWARE_HYPERVISOR_PORT_HB ", %%dx; rep insb", \
+		      "vmcall", X86_FEATURE_VMCALL,			\
+		      "vmmcall", X86_FEATURE_VMW_VMMCALL)
+#endif

arch/x86/kernel/cpu/vmware.c

@@ -30,6 +30,7 @@
 #include <asm/hypervisor.h>
 #include <asm/timer.h>
 #include <asm/apic.h>
+#include <asm/vmware.h>
 
 #undef pr_fmt
 #define pr_fmt(fmt)	"vmware: " fmt
@@ -40,7 +41,6 @@
 #define CPUID_VMWARE_FEATURES_ECX_VMCALL     BIT(1)
 
 #define VMWARE_HYPERVISOR_MAGIC	0x564D5868
-#define VMWARE_HYPERVISOR_PORT	0x5658
 
 #define VMWARE_CMD_GETVERSION    10
 #define VMWARE_CMD_GETHZ         45
@@ -164,6 +164,10 @@ static void __init vmware_set_capabilities(void)
 {
 	setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC);
 	setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+	if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMCALL)
+		setup_force_cpu_cap(X86_FEATURE_VMCALL);
+	else if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMMCALL)
+		setup_force_cpu_cap(X86_FEATURE_VMW_VMMCALL);
 }
 
 static void __init vmware_platform_setup(void)