On 01/29/21 01:59, Ankur Arora wrote:
> As part of the negotiation treat ICH9_LPC_SMI_F_CPU_HOT_UNPLUG as a
> subfeature of feature flag ICH9_LPC_SMI_F_CPU_HOTPLUG, so enable it
> only if the other is also being negotiated.
>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Jordan Justen <jordan.l.jus...@intel.com>
> Cc: Ard Biesheuvel <ard.biesheu...@arm.com>
> Cc: Igor Mammedov <imamm...@redhat.com>
> Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
> Cc: Aaron Young <aaron.yo...@oracle.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
> Signed-off-by: Ankur Arora <ankur.a.ar...@oracle.com>
> ---
> OvmfPkg/SmmControl2Dxe/SmiFeatures.c | 25 ++++++++++++++++++++++---
> 1 file changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/OvmfPkg/SmmControl2Dxe/SmiFeatures.c
> b/OvmfPkg/SmmControl2Dxe/SmiFeatures.c
> index c9d875543205..e70f3f8b58cb 100644
> --- a/OvmfPkg/SmmControl2Dxe/SmiFeatures.c
> +++ b/OvmfPkg/SmmControl2Dxe/SmiFeatures.c
> @@ -29,6 +29,13 @@
> //
> #define ICH9_LPC_SMI_F_CPU_HOTPLUG BIT1
>
> +// The following bit value stands for "enable CPU hot unplug, and inject an
> SMI
(1) s/hot unplug/hot-unplug/
> +// with control value ICH9_APM_CNT_CPU_HOT_UNPLUG upon hot unplug", in the
(2) There is no such thing as ICH9_APM_CNT_CPU_HOT_UNPLUG; we use the
same SMI command value ICH9_APM_CNT_CPU_HOTPLUG (= 4) for unplug.
In QEMU, the macro is called OVMF_CPUHP_SMI_CMD.
(3) s/hot unplug/hot-unplug/.
> +// "etc/smi/supported-features" and "etc/smi/requested-features" fw_cfg
> files.
> +// Is only negotiated alongside ICH9_LPC_SMI_F_CPU_HOTPLUG.
(4) Please drop the last sentence (see more on it below).
> +//
> +#define ICH9_LPC_SMI_F_CPU_HOT_UNPLUG BIT2
> +
> //
> // Provides a scratch buffer (allocated in EfiReservedMemoryType type memory)
> // for the S3 boot script fragment to write to and read from.
> @@ -112,7 +119,8 @@ NegotiateSmiFeatures (
> QemuFwCfgReadBytes (sizeof mSmiFeatures, &mSmiFeatures);
>
> //
> - // We want broadcast SMI, SMI on CPU hotplug, and nothing else.
> + // We want broadcast SMI, SMI on CPU hotplug, on CPU hot-unplug
> + // and nothing else.
> //
> RequestedFeaturesMask = ICH9_LPC_SMI_F_BROADCAST;
> if (!MemEncryptSevIsEnabled ()) {
(5) Please spell out the full expression "SMI on CPU hot-unplug".
> @@ -120,8 +128,18 @@ NegotiateSmiFeatures (
> // For now, we only support hotplug with SEV disabled.
> //
> RequestedFeaturesMask |= ICH9_LPC_SMI_F_CPU_HOTPLUG;
> + RequestedFeaturesMask |= ICH9_LPC_SMI_F_CPU_HOT_UNPLUG;
> }
> mSmiFeatures &= RequestedFeaturesMask;
> +
> + if (!(mSmiFeatures & ICH9_LPC_SMI_F_CPU_HOTPLUG) &&
> + (mSmiFeatures & ICH9_LPC_SMI_F_CPU_HOT_UNPLUG)) {
> + DEBUG ((DEBUG_WARN, "%a CPU host-features %Lx, requested mask %Lx\n",
> + __FUNCTION__, mSmiFeatures, RequestedFeaturesMask));
> +
> + mSmiFeatures &= ~ICH9_LPC_SMI_F_CPU_HOT_UNPLUG;
> + }
> +
> QemuFwCfgSelectItem (mRequestedFeaturesItem);
> QemuFwCfgWriteBytes (sizeof mSmiFeatures, &mSmiFeatures);
>
(6) Please drop this hunk. We don't try to be smarter than QEMU, in
general, whenever we perform feature negotiation.
For example, the pre-patch code doesn't attempt to notice if QEMU
acknowledges ICH9_LPC_SMI_F_CPU_HOTPLUG but not ICH9_LPC_SMI_F_BROADCAST.
> @@ -162,8 +180,9 @@ NegotiateSmiFeatures (
> if ((mSmiFeatures & ICH9_LPC_SMI_F_CPU_HOTPLUG) == 0) {
> DEBUG ((DEBUG_INFO, "%a: CPU hotplug not negotiated\n", __FUNCTION__));
> } else {
> - DEBUG ((DEBUG_INFO, "%a: CPU hotplug with SMI negotiated\n",
> - __FUNCTION__));
> + DEBUG ((DEBUG_INFO, "%a: CPU hotplug%s with SMI negotiated\n",
> + __FUNCTION__,
> + (mSmiFeatures & ICH9_LPC_SMI_F_CPU_HOT_UNPLUG) ? ", unplug" : ""));
> }
>
> //
>
(7) Rather than combining these two in a common debug message, please
just add a separate "if" that follows the whole pattern seen with
ICH9_LPC_SMI_F_CPU_HOTPLUG. Thus, for each feature bit we care about,
we'll have a dedicated log message, saying yes or no.
Thanks!
Laszlo
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