diff mbox series

[v11,8/8] x86/vmware: Add TDX hypercall support

Message ID 20240613191650.9913-9-alexey.makhalov@broadcom.com (mailing list archive)
State Not Applicable
Headers show
Series VMware hypercalls enhancements | expand

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Commit Message

Alexey Makhalov June 13, 2024, 7:16 p.m. UTC 
VMware hypercalls use I/O port, VMCALL or VMMCALL instructions.
Add __tdx_hypercall path to support TDX guests.

No change in high bandwidth hypercalls, as only low bandwidth
ones are supported for TDX guests.

Co-developed-by: Tim Merrifield <tim.merrifield@broadcom.com>
Signed-off-by: Tim Merrifield <tim.merrifield@broadcom.com>
Signed-off-by: Alexey Makhalov <alexey.makhalov@broadcom.com>
---
 arch/x86/include/asm/vmware.h | 45 +++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/vmware.c  | 51 +++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

Comments

Dave Hansen June 14, 2024, 4:03 p.m. UTC | #1 
On 6/13/24 12:16, Alexey Makhalov wrote:
> +unsigned long vmware_tdx_hypercall(unsigned long cmd,
> +				   unsigned long in1, unsigned long in3,
> +				   unsigned long in4, unsigned long in5,
> +				   u32 *out1, u32 *out2, u32 *out3,
> +				   u32 *out4, u32 *out5)
> +{
> +	struct tdx_module_args args;
> +
> +	if (!hypervisor_is_type(X86_HYPER_VMWARE)) {
> +		pr_warn_once("Incorrect usage\n");
> +		return ULONG_MAX;
> +	}
> +
> +	if (cmd & ~VMWARE_CMD_MASK) {
> +		pr_warn_once("Out of range command %lx\n", cmd);
> +		return ULONG_MAX;
> +	}
> +
> +	args.rbx = in1;
> +	args.rdx = in3;
> +	args.rsi = in4;
> +	args.rdi = in5;
> +	args.r10 = VMWARE_TDX_VENDOR_LEAF;
> +	args.r11 = VMWARE_TDX_HCALL_FUNC;
> +	args.r12 = VMWARE_HYPERVISOR_MAGIC;
> +	args.r13 = cmd;
> +	args.r15 = 0; /* CPL */

I believe this leaks stack data into the hypervisor.  Or did I miss the
zeroing of rcx/r8/r9/r14?

You need to zero out all of 'args' somehow.
Borislav Petkov June 14, 2024, 4:14 p.m. UTC | #2 
On Fri, Jun 14, 2024 at 09:03:22AM -0700, Dave Hansen wrote:
> On 6/13/24 12:16, Alexey Makhalov wrote:
> > +unsigned long vmware_tdx_hypercall(unsigned long cmd,
> > +				   unsigned long in1, unsigned long in3,
> > +				   unsigned long in4, unsigned long in5,
> > +				   u32 *out1, u32 *out2, u32 *out3,
> > +				   u32 *out4, u32 *out5)
> > +{
> > +	struct tdx_module_args args;
> > +
> > +	if (!hypervisor_is_type(X86_HYPER_VMWARE)) {
> > +		pr_warn_once("Incorrect usage\n");
> > +		return ULONG_MAX;
> > +	}
> > +
> > +	if (cmd & ~VMWARE_CMD_MASK) {
> > +		pr_warn_once("Out of range command %lx\n", cmd);
> > +		return ULONG_MAX;
> > +	}
> > +
> > +	args.rbx = in1;
> > +	args.rdx = in3;
> > +	args.rsi = in4;
> > +	args.rdi = in5;
> > +	args.r10 = VMWARE_TDX_VENDOR_LEAF;
> > +	args.r11 = VMWARE_TDX_HCALL_FUNC;
> > +	args.r12 = VMWARE_HYPERVISOR_MAGIC;
> > +	args.r13 = cmd;
> > +	args.r15 = 0; /* CPL */
> 
> I believe this leaks stack data into the hypervisor.  Or did I miss the
> zeroing of rcx/r8/r9/r14?
> 
> You need to zero out all of 'args' somehow.

You mean like this:

	struct tdx_module_args args = {};

?
Dave Hansen June 14, 2024, 4:19 p.m. UTC | #3 
On 6/14/24 09:14, Borislav Petkov wrote:
> On Fri, Jun 14, 2024 at 09:03:22AM -0700, Dave Hansen wrote:
...
>> You need to zero out all of 'args' somehow.
> 
> You mean like this:
> 
> 	struct tdx_module_args args = {};
> 
> ?

Yes, or do all the assignments with the initializer.  We seem to do it
both ways, so whatever works.
Alexey Makhalov June 14, 2024, 6:32 p.m. UTC | #4 
On 6/14/24 9:19 AM, Dave Hansen wrote:
> On 6/14/24 09:14, Borislav Petkov wrote:
>> On Fri, Jun 14, 2024 at 09:03:22AM -0700, Dave Hansen wrote:
> ...
>>> You need to zero out all of 'args' somehow.
>>
>> You mean like this:
>>
>> 	struct tdx_module_args args = {};
>>
>> ?
> 
> Yes, or do all the assignments with the initializer.  We seem to do it
> both ways, so whatever works.

Thanks Dave for pointing that out. I missed that at v7.
Borislav Petkov June 14, 2024, 7:09 p.m. UTC | #5 
On Fri, Jun 14, 2024 at 11:32:16AM -0700, Alexey Makhalov wrote:
> 
> 
> On 6/14/24 9:19 AM, Dave Hansen wrote:
> > On 6/14/24 09:14, Borislav Petkov wrote:
> > > On Fri, Jun 14, 2024 at 09:03:22AM -0700, Dave Hansen wrote:
> > ...
> > > > You need to zero out all of 'args' somehow.
> > > 
> > > You mean like this:
> > > 
> > > 	struct tdx_module_args args = {};
> > > 
> > > ?
> > 
> > Yes, or do all the assignments with the initializer.  We seem to do it
> > both ways, so whatever works.
> 
> Thanks Dave for pointing that out. I missed that at v7.

Ok, I'll fold this struct initialization oneliner into the last patch.
Alexey Makhalov June 14, 2024, 10 p.m. UTC | #6 
On 6/14/24 12:09 PM, Borislav Petkov wrote:
> On Fri, Jun 14, 2024 at 11:32:16AM -0700, Alexey Makhalov wrote:
>>
>>
>> On 6/14/24 9:19 AM, Dave Hansen wrote:
>>> On 6/14/24 09:14, Borislav Petkov wrote:
>>>> On Fri, Jun 14, 2024 at 09:03:22AM -0700, Dave Hansen wrote:
>>> ...
>>>>> You need to zero out all of 'args' somehow.
>>>>
>>>> You mean like this:
>>>>
>>>> 	struct tdx_module_args args = {};
>>>>
>>>> ?
>>>
>>> Yes, or do all the assignments with the initializer.  We seem to do it
>>> both ways, so whatever works.
>>
>> Thanks Dave for pointing that out. I missed that at v7.
> 
> Ok, I'll fold this struct initialization oneliner into the last patch.
> 
Thanks!
diff mbox series

Patch

diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h
index d83444f03969..c9cf43d5ef23 100644
--- a/arch/x86/include/asm/vmware.h
+++ b/arch/x86/include/asm/vmware.h
@@ -18,6 +18,12 @@ 
  * arg2 - Hypercall command
  * arg3 bits [15:0] - Port number, LB and direction flags
  *
+ * - Low bandwidth TDX hypercalls (x86_64 only) are similar to LB
+ * hypercalls. They also have up to 6 input and 6 output on registers
+ * arguments, with different argument to register mapping:
+ * %r12 (arg0), %rbx (arg1), %r13 (arg2), %rdx (arg3),
+ * %rsi (arg4), %rdi (arg5).
+ *
  * - High bandwidth (HB) hypercalls are I/O port based only. They have
  * up to 7 input and 7 output arguments passed and returned using
  * registers: %eax (arg0), %ebx (arg1), %ecx (arg2), %edx (arg3),
@@ -54,6 +60,12 @@ 
 #define VMWARE_CMD_GETHZ		45
 #define VMWARE_CMD_GETVCPU_INFO		68
 #define VMWARE_CMD_STEALCLOCK		91
+/*
+ * Hypercall command mask:
+ *   bits [6:0] command, range [0, 127]
+ *   bits [19:16] sub-command, range [0, 15]
+ */
+#define VMWARE_CMD_MASK			0xf007fU
 
 #define CPUID_VMWARE_FEATURES_ECX_VMMCALL	BIT(0)
 #define CPUID_VMWARE_FEATURES_ECX_VMCALL	BIT(1)
@@ -64,6 +76,15 @@  extern unsigned long vmware_hypercall_slow(unsigned long cmd,
 					   u32 *out1, u32 *out2, u32 *out3,
 					   u32 *out4, u32 *out5);
 
+#define VMWARE_TDX_VENDOR_LEAF 0x1af7e4909ULL
+#define VMWARE_TDX_HCALL_FUNC  1
+
+extern unsigned long vmware_tdx_hypercall(unsigned long cmd,
+					  unsigned long in1, unsigned long in3,
+					  unsigned long in4, unsigned long in5,
+					  u32 *out1, u32 *out2, u32 *out3,
+					  u32 *out4, u32 *out5);
+
 /*
  * The low bandwidth call. The low word of %edx is presumed to have OUT bit
  * set. The high word of %edx may contain input data from the caller.
@@ -79,6 +100,10 @@  unsigned long vmware_hypercall1(unsigned long cmd, unsigned long in1)
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, 0, 0, 0,
+					    NULL, NULL, NULL, NULL, NULL);
+
 	if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
 		return vmware_hypercall_slow(cmd, in1, 0, 0, 0,
 					     NULL, NULL, NULL, NULL, NULL);
@@ -100,6 +125,10 @@  unsigned long vmware_hypercall3(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, 0, 0, 0,
+					    out1, out2, NULL, NULL, NULL);
+
 	if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
 		return vmware_hypercall_slow(cmd, in1, 0, 0, 0,
 					     out1, out2, NULL, NULL, NULL);
@@ -121,6 +150,10 @@  unsigned long vmware_hypercall4(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, 0, 0, 0,
+					    out1, out2, out3, NULL, NULL);
+
 	if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
 		return vmware_hypercall_slow(cmd, in1, 0, 0, 0,
 					     out1, out2, out3, NULL, NULL);
@@ -143,6 +176,10 @@  unsigned long vmware_hypercall5(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, in3, in4, in5,
+					    NULL, out2, NULL, NULL, NULL);
+
 	if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
 		return vmware_hypercall_slow(cmd, in1, in3, in4, in5,
 					     NULL, out2, NULL, NULL, NULL);
@@ -167,6 +204,10 @@  unsigned long vmware_hypercall6(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, in3, 0, 0,
+					    NULL, out2, out3, out4, out5);
+
 	if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
 		return vmware_hypercall_slow(cmd, in1, in3, 0, 0,
 					     NULL, out2, out3, out4, out5);
@@ -191,6 +232,10 @@  unsigned long vmware_hypercall7(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, in3, in4, in5,
+					    out1, out2, out3, NULL, NULL);
+
 	if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
 		return vmware_hypercall_slow(cmd, in1, in3, in4, in5,
 					     out1, out2, out3, NULL, NULL);
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index d24ba03b30b8..708048b8a095 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -477,6 +477,57 @@  static bool __init vmware_legacy_x2apic_available(void)
 		(eax & GETVCPU_INFO_LEGACY_X2APIC);
 }
 
+#ifdef CONFIG_INTEL_TDX_GUEST
+/*
+ * TDCALL[TDG.VP.VMCALL] uses %rax (arg0) and %rcx (arg2). Therefore,
+ * we remap those registers to %r12 and %r13, respectively.
+ */
+unsigned long vmware_tdx_hypercall(unsigned long cmd,
+				   unsigned long in1, unsigned long in3,
+				   unsigned long in4, unsigned long in5,
+				   u32 *out1, u32 *out2, u32 *out3,
+				   u32 *out4, u32 *out5)
+{
+	struct tdx_module_args args;
+
+	if (!hypervisor_is_type(X86_HYPER_VMWARE)) {
+		pr_warn_once("Incorrect usage\n");
+		return ULONG_MAX;
+	}
+
+	if (cmd & ~VMWARE_CMD_MASK) {
+		pr_warn_once("Out of range command %lx\n", cmd);
+		return ULONG_MAX;
+	}
+
+	args.rbx = in1;
+	args.rdx = in3;
+	args.rsi = in4;
+	args.rdi = in5;
+	args.r10 = VMWARE_TDX_VENDOR_LEAF;
+	args.r11 = VMWARE_TDX_HCALL_FUNC;
+	args.r12 = VMWARE_HYPERVISOR_MAGIC;
+	args.r13 = cmd;
+	args.r15 = 0; /* CPL */
+
+	__tdx_hypercall(&args);
+
+	if (out1)
+		*out1 = args.rbx;
+	if (out2)
+		*out2 = args.r13;
+	if (out3)
+		*out3 = args.rdx;
+	if (out4)
+		*out4 = args.rsi;
+	if (out5)
+		*out5 = args.rdi;
+
+	return args.r12;
+}
+EXPORT_SYMBOL_GPL(vmware_tdx_hypercall);
+#endif
+
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 static void vmware_sev_es_hcall_prepare(struct ghcb *ghcb,
 					struct pt_regs *regs)