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From: Long Li <longli@microsoft.com>
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Subject: RE: [PATCH v2 1/1] x86/hyperv: Use Hyper-V entropy to seed guest
 random number generator
Thread-Topic: [PATCH v2 1/1] x86/hyperv: Use Hyper-V entropy to seed guest
 random number generator
Thread-Index: AQHacMAmGe+doP7+JUap2rkXt0C9bbE1H/cA
Date: Wed, 13 Mar 2024 04:50:59 +0000
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> +void __init ms_hyperv_late_init(void)
> +{
> +       struct acpi_table_header *header;
> +       acpi_status status;
> +       u8 *randomdata;
> +       u32 length, i;
> +
> +       /*
> +        * Seed the Linux random number generator with entropy provided b=
y
> +        * the Hyper-V host in ACPI table OEM0.  It would be nice to do t=
his
> +        * even earlier in ms_hyperv_init_platform(), but the ACPI subsys=
tem
> +        * isn't set up at that point. Skip if booted via EFI as generic =
EFI
> +        * code has already done some seeding using the EFI RNG protocol.
> +        */
> +       if (!IS_ENABLED(CONFIG_ACPI) || efi_enabled(EFI_BOOT))
> +               return;
> +
> +       status =3D acpi_get_table("OEM0", 0, &header);
> +       if (ACPI_FAILURE(status) || !header)
> +               return;

Should we call acpi_put_table() if header =3D=3D 0? It will also be helpful=
 doing a pr_info() here so user knows that hyper-v random number is not use=
d.