From 778832bcad33512ae09bbf7235a1ddcfa7403083 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Mon, 7 Oct 2019 14:05:28 +0200 Subject: UefiCpuPkg/MpInitLib: honor the platform's boot CPU count in AP detection - If a platform boots such that the boot CPU count is smaller than PcdCpuMaxLogicalProcessorNumber, then the platform cannot use the "fast AP detection" logic added in commit 6e1987f19af7. (Which has been documented as a subset of use case (2) in the previous patch.) Said logic depends on the boot CPU count being equal to PcdCpuMaxLogicalProcessorNumber. If the equality does not hold, the platform either has to wait too long, or risk missing APs due to an early timeout. - The platform may not be able to use the variant added in commit 0594ec417c89 either. (Which has been documented as use case (1) in the previous patch.) See commit 861218740d6d. When OVMF runs on QEMU/KVM, APs may check in with the BSP in arbitrary order, plus the individual AP may take arbitrarily long to check-in. If "NumApsExecuting" falls to zero mid-enumeration, APs will be missed. Allow platforms to specify the exact boot CPU count, independently of PcdCpuMaxLogicalProcessorNumber. In this mode, the BSP waits for all APs to check-in regardless of timeout. If at least one AP fails to check-in, then the AP enumeration hangs forever. That is the desired behavior when the exact boot CPU count is known in advance. (A hung boot is better than an AP checking-in after timeout, and executing code from released storage.) Cc: Eric Dong Cc: Ray Ni Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1515 Signed-off-by: Laszlo Ersek Reviewed-by: Ray Ni --- UefiCpuPkg/UefiCpuPkg.uni | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'UefiCpuPkg/UefiCpuPkg.uni') diff --git a/UefiCpuPkg/UefiCpuPkg.uni b/UefiCpuPkg/UefiCpuPkg.uni index fbf7680726..a7e279c5cb 100644 --- a/UefiCpuPkg/UefiCpuPkg.uni +++ b/UefiCpuPkg/UefiCpuPkg.uni @@ -37,6 +37,10 @@ #string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuApInitTimeOutInMicroSeconds_HELP #language en-US "Specifies timeout value in microseconds for the BSP to detect all APs for the first time." +#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuBootLogicalProcessorNumber_PROMPT #language en-US "Number of Logical Processors available after platform reset." + +#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuBootLogicalProcessorNumber_HELP #language en-US "Specifies the number of Logical Processors that are available in the preboot environment after platform reset, including BSP and APs." + #string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuMicrocodePatchAddress_PROMPT #language en-US "Microcode Region base address." #string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuMicrocodePatchAddress_HELP #language en-US "Specifies the base address of the first microcode Patch in the microcode Region." -- cgit v1.2.3