From 5ce45c7a2b15cda0a4d8f6c38c4036df25dc9c42 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Thu, 26 Jan 2017 02:44:15 +0100 Subject: [PATCH] hw/isa/lpc_ich9: add broadcast SMI feature The generic edk2 SMM infrastructure prefers EFI_SMM_CONTROL2_PROTOCOL.Trigger() to inject an SMI on each processor. If Trigger() only brings the current processor into SMM, then edk2 handles it in the following ways: (1) If Trigger() is executed by the BSP (which is guaranteed before ExitBootServices(), but is not necessarily true at runtime), then: (a) If edk2 has been configured for "traditional" SMM synchronization, then the BSP sends directed SMIs to the APs with APIC delivery, bringing them into SMM individually. Then the BSP runs the SMI handler / dispatcher. (b) If edk2 has been configured for "relaxed" SMM synchronization, then the APs that are not already in SMM are not brought in, and the BSP runs the SMI handler / dispatcher. (2) If Trigger() is executed by an AP (which is possible after ExitBootServices(), and can be forced e.g. by "taskset -c 1 efibootmgr"), then the AP in question brings in the BSP with a directed SMI, and the BSP runs the SMI handler / dispatcher. The smaller problem with (1a) and (2) is that the BSP and AP synchronization is slow. For example, the "taskset -c 1 efibootmgr" command from (2) can take more than 3 seconds to complete, because efibootmgr accesses non-volatile UEFI variables intensively. The larger problem is that QEMU's current behavior diverges from the behavior usually seen on physical hardware, and that keeps exposing obscure corner cases, race conditions and other instabilities in edk2, which generally expects / prefers a software SMI to affect all CPUs at once. Therefore introduce the "broadcast SMI" feature that causes QEMU to inject the SMI on all VCPUs. While the original posting of this patch only intended to speed up (2), based on our recent "stress testing" of SMM this patch actually provides functional improvements. Cc: "Michael S. Tsirkin" Cc: Gerd Hoffmann Cc: Igor Mammedov Cc: Paolo Bonzini Signed-off-by: Laszlo Ersek Reviewed-by: Michael S. Tsirkin Reviewed-by: Igor Mammedov Message-Id: <20170126014416.11211-3-lersek@redhat.com> Signed-off-by: Paolo Bonzini --- hw/isa/lpc_ich9.c | 10 +++++++++- include/hw/i386/ich9.h | 3 +++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c index 376b7801a4..ced6f803a4 100644 --- a/hw/isa/lpc_ich9.c +++ b/hw/isa/lpc_ich9.c @@ -437,7 +437,15 @@ static void ich9_apm_ctrl_changed(uint32_t val, void *arg) /* SMI_EN = PMBASE + 30. SMI control and enable register */ if (lpc->pm.smi_en & ICH9_PMIO_SMI_EN_APMC_EN) { - cpu_interrupt(current_cpu, CPU_INTERRUPT_SMI); + if (lpc->smi_negotiated_features & + (UINT64_C(1) << ICH9_LPC_SMI_F_BROADCAST_BIT)) { + CPUState *cs; + CPU_FOREACH(cs) { + cpu_interrupt(cs, CPU_INTERRUPT_SMI); + } + } else { + cpu_interrupt(current_cpu, CPU_INTERRUPT_SMI); + } } } diff --git a/include/hw/i386/ich9.h b/include/hw/i386/ich9.h index da11187271..18dcca7ebc 100644 --- a/include/hw/i386/ich9.h +++ b/include/hw/i386/ich9.h @@ -250,4 +250,7 @@ Object *ich9_lpc_find(void); #define ICH9_SMB_HST_D1 0x06 #define ICH9_SMB_HOST_BLOCK_DB 0x07 +/* bit positions used in fw_cfg SMI feature negotiation */ +#define ICH9_LPC_SMI_F_BROADCAST_BIT 0 + #endif /* HW_ICH9_H */