On 2/27/2025 3:03 PM, Easwar Hariharan wrote:

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

quoted

Factor out the check for enabling auto eoi, to be reused in root
partition code.

Signed-off-by: Nuno Das Neves <redacted>
---
 drivers/hv/hv.c                | 12 +-----------
 include/asm-generic/mshyperv.h | 13 +++++++++++++
 2 files changed, 14 insertions(+), 11 deletions(-)

<snip>

quoted

diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 258034dfd829..1f46d19a16aa 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h

@@ -77,6 +77,19 @@ extern u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 input2);
 bool hv_isolation_type_snp(void);
 bool hv_isolation_type_tdx(void);
 
+/*
+ * On architectures where Hyper-V doesn't support AEOI (e.g., ARM64),
+ * it doesn't provide a recommendation flag and AEOI must be disabled.
+ */
+static inline bool hv_recommend_using_aeoi(void)
+{
+#ifdef HV_DEPRECATING_AEOI_RECOMMENDED
+	return !(ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED);
+#else
+	return false;
+#endif
+}
+

I must be missing something very basic here, and if so, I apologize, and please enlighten me.

HV_DEPRECATING_AEOI_RECOMMENDED is defined as BIT(9) in include/hyperv/hvgdk_mini.h, and
asm-generic/mshyperv.h includes that via include/hyperv/hvhdk.h.

If this is the case, when would HV_DEPRECATING_AEOI_RECOMMENDED ever be not defined?
If it's always defined, do we need the #ifdef?

HV_DEPRECATING_AEOI_RECOMMENDED is only defined on x86 (it used to live in x86 hyperv-tlfs.h).
It lives inside a #if defined(CONFIG_X86) block in hvgdk_mini.h. It is a bit confusing since
it is surrounded by other x86-only definitions which are prefixed with HV_X64_.

Thanks
Nuno

Thanks,
Easwar (he/him)