[PATCH v3 1/4] x86/vmware: Update platform detection code for VMCALL/VMMCALL hypercalls

From: "Thomas Hellström (VMware)" <thomas_os@shipmail.org>
To: linux-kernel@vger.kernel.org
Cc: pv-drivers@vmware.com, linux-graphics-maintainer@vmware.com,
	Thomas Hellstrom <thellstrom@vmware.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Doug Covelli <dcovelli@vmware.com>
Subject: [PATCH v3 1/4] x86/vmware: Update platform detection code for VMCALL/VMMCALL hypercalls
Date: Wed, 28 Aug 2019 10:03:50 +0200	[thread overview]
Message-ID: <20190828080353.12658-2-thomas_os@shipmail.org> (raw)
In-Reply-To: <20190828080353.12658-1-thomas_os@shipmail.org>

From: Thomas Hellstrom <thellstrom@vmware.com>

Vmware has historically used an "inl" instruction for this, but recent
hardware versions support using VMCALL/VMMCALL instead, so use this method
if supported at platform detection time. Explicitly code separate macro
versions since the alternatives self-patching has not been performed at
platform detection time.

Also put tighter constraints on the assembly input parameters.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <x86@kernel.org>
Co-developed-by: Doug Covelli <dcovelli@vmware.com>
Signed-off-by: Doug Covelli <dcovelli@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Doug Covelli <dcovelli@vmware.com>
---
 arch/x86/kernel/cpu/vmware.c | 88 +++++++++++++++++++++++++++++-------
 1 file changed, 71 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 3c648476d4fb..757dded223af 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -34,30 +34,65 @@
 #undef pr_fmt
 #define pr_fmt(fmt)	"vmware: " fmt
 
-#define CPUID_VMWARE_INFO_LEAF	0x40000000
+#define CPUID_VMWARE_INFO_LEAF               0x40000000
+#define CPUID_VMWARE_FEATURES_LEAF           0x40000010
+#define CPUID_VMWARE_FEATURES_ECX_VMMCALL    BIT(0)
+#define CPUID_VMWARE_FEATURES_ECX_VMCALL     BIT(1)
+
 #define VMWARE_HYPERVISOR_MAGIC	0x564D5868
 #define VMWARE_HYPERVISOR_PORT	0x5658
 
-#define VMWARE_PORT_CMD_GETVERSION	10
-#define VMWARE_PORT_CMD_GETHZ		45
-#define VMWARE_PORT_CMD_GETVCPU_INFO	68
-#define VMWARE_PORT_CMD_LEGACY_X2APIC	3
-#define VMWARE_PORT_CMD_VCPU_RESERVED	31
+#define VMWARE_CMD_GETVERSION    10
+#define VMWARE_CMD_GETHZ         45
+#define VMWARE_CMD_GETVCPU_INFO  68
+#define VMWARE_CMD_LEGACY_X2APIC  3
+#define VMWARE_CMD_VCPU_RESERVED 31
 
 #define VMWARE_PORT(cmd, eax, ebx, ecx, edx)				\
 	__asm__("inl (%%dx)" :						\
-			"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :	\
-			"0"(VMWARE_HYPERVISOR_MAGIC),			\
-			"1"(VMWARE_PORT_CMD_##cmd),			\
-			"2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) :	\
-			"memory");
+		"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :		\
+		"a"(VMWARE_HYPERVISOR_MAGIC),				\
+		"c"(VMWARE_CMD_##cmd),					\
+		"d"(VMWARE_HYPERVISOR_PORT), "b"(UINT_MAX) :		\
+		"memory")
+
+#define VMWARE_VMCALL(cmd, eax, ebx, ecx, edx)				\
+	__asm__("vmcall" :						\
+		"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :		\
+		"a"(VMWARE_HYPERVISOR_MAGIC),				\
+		"c"(VMWARE_CMD_##cmd),					\
+		"d"(0), "b"(UINT_MAX) :					\
+		"memory")
+
+#define VMWARE_VMMCALL(cmd, eax, ebx, ecx, edx)                         \
+	__asm__("vmmcall" :						\
+		"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :		\
+		"a"(VMWARE_HYPERVISOR_MAGIC),				\
+		"c"(VMWARE_CMD_##cmd),					\
+		"d"(0), "b"(UINT_MAX) :					\
+		"memory")
+
+#define VMWARE_CMD(cmd, eax, ebx, ecx, edx) do {		\
+	switch (vmware_hypercall_mode) {			\
+	case CPUID_VMWARE_FEATURES_ECX_VMCALL:			\
+		VMWARE_VMCALL(cmd, eax, ebx, ecx, edx);		\
+		break;						\
+	case CPUID_VMWARE_FEATURES_ECX_VMMCALL:			\
+		VMWARE_VMMCALL(cmd, eax, ebx, ecx, edx);	\
+		break;						\
+	default:						\
+		VMWARE_PORT(cmd, eax, ebx, ecx, edx);		\
+		break;						\
+	}							\
+	} while (0)
 
 static unsigned long vmware_tsc_khz __ro_after_init;
+static u8 vmware_hypercall_mode     __ro_after_init;
 
 static inline int __vmware_platform(void)
 {
 	uint32_t eax, ebx, ecx, edx;
-	VMWARE_PORT(GETVERSION, eax, ebx, ecx, edx);
+	VMWARE_CMD(GETVERSION, eax, ebx, ecx, edx);
 	return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
 }
 
@@ -136,7 +171,7 @@ static void __init vmware_platform_setup(void)
 	uint32_t eax, ebx, ecx, edx;
 	uint64_t lpj, tsc_khz;
 
-	VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
+	VMWARE_CMD(GETHZ, eax, ebx, ecx, edx);
 
 	if (ebx != UINT_MAX) {
 		lpj = tsc_khz = eax | (((uint64_t)ebx) << 32);
@@ -174,10 +209,21 @@ static void __init vmware_platform_setup(void)
 	vmware_set_capabilities();
 }
 
+static u8 vmware_select_hypercall(void)
+{
+	int eax, ebx, ecx, edx;
+
+	cpuid(CPUID_VMWARE_FEATURES_LEAF, &eax, &ebx, &ecx, &edx);
+	return (ecx & (CPUID_VMWARE_FEATURES_ECX_VMMCALL |
+		       CPUID_VMWARE_FEATURES_ECX_VMCALL));
+}
+
 /*
  * While checking the dmi string information, just checking the product
  * serial key should be enough, as this will always have a VMware
  * specific string when running under VMware hypervisor.
+ * If !boot_cpu_has(X86_FEATURE_HYPERVISOR), vmware_hypercall_mode
+ * intentionally defaults to 0.
  */
 static uint32_t __init vmware_platform(void)
 {
@@ -187,8 +233,16 @@ static uint32_t __init vmware_platform(void)
 
 		cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
 		      &hyper_vendor_id[1], &hyper_vendor_id[2]);
-		if (!memcmp(hyper_vendor_id, "VMwareVMware", 12))
+		if (!memcmp(hyper_vendor_id, "VMwareVMware", 12)) {
+			if (eax >= CPUID_VMWARE_FEATURES_LEAF)
+				vmware_hypercall_mode =
+					vmware_select_hypercall();
+
+			pr_info("hypercall mode: 0x%02x\n",
+				(unsigned int) vmware_hypercall_mode);
+
 			return CPUID_VMWARE_INFO_LEAF;
+		}
 	} else if (dmi_available && dmi_name_in_serial("VMware") &&
 		   __vmware_platform())
 		return 1;
@@ -200,9 +254,9 @@ static uint32_t __init vmware_platform(void)
 static bool __init vmware_legacy_x2apic_available(void)
 {
 	uint32_t eax, ebx, ecx, edx;
-	VMWARE_PORT(GETVCPU_INFO, eax, ebx, ecx, edx);
-	return (eax & (1 << VMWARE_PORT_CMD_VCPU_RESERVED)) == 0 &&
-	       (eax & (1 << VMWARE_PORT_CMD_LEGACY_X2APIC)) != 0;
+	VMWARE_CMD(GETVCPU_INFO, eax, ebx, ecx, edx);
+	return (eax & (1 << VMWARE_CMD_VCPU_RESERVED)) == 0 &&
+	       (eax & (1 << VMWARE_CMD_LEGACY_X2APIC)) != 0;
 }
 
 const __initconst struct hypervisor_x86 x86_hyper_vmware = {
-- 
2.20.1

