On 3/6/2025 11:05 AM, Michael Kelley wrote:

From: Nuno Das Neves <redacted> Sent: Thursday, February 27, 2025 4:21 PM

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On 2/26/2025 9:56 PM, Easwar Hariharan wrote:

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On 2/26/2025 3:07 PM, Nuno Das Neves wrote:

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These non-nested msr and fast hypercall functions are present in x86,
but they must be available in both architetures for the root partition

nit: *architectures*

Thanks!

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driver code.

Signed-off-by: Nuno Das Neves <redacted>
---
 arch/arm64/hyperv/hv_core.c       | 17 +++++++++++++++++
 arch/arm64/include/asm/mshyperv.h | 12 ++++++++++++
 include/asm-generic/mshyperv.h    |  2 ++
 3 files changed, 31 insertions(+)

diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
index 69004f619c57..e33a9e3c366a 100644
--- a/arch/arm64/hyperv/hv_core.c
+++ b/arch/arm64/hyperv/hv_core.c

@@ -53,6 +53,23 @@ u64 hv_do_fast_hypercall8(u16 code, u64 input)
 }
 EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8);

+/*
+ * hv_do_fast_hypercall16 -- Invoke the specified hypercall
+ * with arguments in registers instead of physical memory.
+ * Avoids the overhead of virt_to_phys for simple hypercalls.
+ */
+u64 hv_do_fast_hypercall16(u16 code, u64 input1, u64 input2)
+{
+	struct arm_smccc_res	res;
+	u64			control;
+
+	control = (u64)code | HV_HYPERCALL_FAST_BIT;
+
+	arm_smccc_1_1_hvc(HV_FUNC_ID, control, input1, input2, &res);
+	return res.a0;
+}
+EXPORT_SYMBOL_GPL(hv_do_fast_hypercall16);
+

I'd like this to have been in arch/arm64/include/asm/mshyperv.h like its x86
counterpart, but that's just my personal liking of symmetry. I see why it's here
with its slow and 8-byte brethren.

Good point, I don't see a good reason this can't be in the header.

I was trying to remember if there was some reason I originally put
hv_do_hypercall() and hv_do_fast_hypercall8() in the .c file instead of
the header like on x86. But I don't remember a reason. During
development, the code changed several times, and there might have
been a reason that didn't persistent in the version that was finally
accepted upstream.

My only comment is that hv_do_hypercall() and the 8 and 16 "fast"
versions should probably stay together one place on the arm64 side,
even if it doesn't match x86.

I think I'll just keep them together here for now then. They
could be moved to the header in future if it seems worth doing.

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 /*
  * Set a single VP register to a 64-bit value.
  */

diff --git a/arch/arm64/include/asm/mshyperv.h

b/arch/arm64/include/asm/mshyperv.h

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index 2e2f83bafcfb..2a900ba00622 100644

--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h

@@ -40,6 +40,18 @@ static inline u64 hv_get_msr(unsigned int reg)
 	return hv_get_vpreg(reg);
 }

+/*
+ * Nested is not supported on arm64
+ */
+static inline void hv_set_non_nested_msr(unsigned int reg, u64 value)
+{
+	hv_set_msr(reg, value);
+}

empty line preferred here, also reported by checkpatch

Good point, missed that one...

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+static inline u64 hv_get_non_nested_msr(unsigned int reg)
+{
+	return hv_get_msr(reg);
+}
+
 /* SMCCC hypercall parameters */
 #define HV_SMCCC_FUNC_NUMBER	1
 #define HV_FUNC_ID	ARM_SMCCC_CALL_VAL(			\

diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index c020d5d0ec2a..258034dfd829 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h

@@ -72,6 +72,8 @@ extern void * __percpu *hyperv_pcpu_output_arg;

 extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
 extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
+extern u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 input2);
+

checkpatch warns against putting externs in header files, and FWIW, if

hv_do_fast_hypercall16()

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for arm64 were in arch/arm64/include/asm/mshyperv.h like its x86 counterpart, you

probably

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wouldn't need this?

Yes I wondered about that warning. That's true, if I just put it in the arm64 header
then this won't be needed at all, so I might just do that!

I always thought the checkpatch warning was simply that "extern" on a function
declaration is superfluous. You can omit "extern" and nothing changes. Of
course, the same is not true for data items.
Good point, I think I'll clean up these "extern"s in the next version.

Nuno

Michael

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 bool hv_isolation_type_snp(void);
 bool hv_isolation_type_tdx(void);