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Date: Thu, 16 Nov 2017 08:26:43 +0100 From: Jan Kiszka <jan.kiszka@...mens.com> To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com> Cc: x86@...nel.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, jailhouse-dev@...glegroups.com Subject: [PATCH 01/10] x86/apic: Install an empty physflat_init_apic_ldr From: Jan Kiszka <jan.kiszka@...mens.com> As the comment already stated, there is no need for setting up LDR in physflat mode as it remains unused. flat_init_apic_ldr only served as a placeholder for a nop operation so far, causing no harm. That will change when running over the Jailhouse hypervisor. Here we must not touch LDR in a way that destroys the mapping originally set up by the Linux root cell. Jailhouse enforces this setting in order to efficiently validate any IPI requests sent by a cell. Avoid a needless clash caused by flat_init_apic_ldr by installing a true nop handler. Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com> --- arch/x86/kernel/apic/apic_flat_64.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c index aa85690e9b64..34bfdfe29a04 100644 --- a/arch/x86/kernel/apic/apic_flat_64.c +++ b/arch/x86/kernel/apic/apic_flat_64.c @@ -218,6 +218,11 @@ static int physflat_acpi_madt_oem_check(char *oem_id, char *oem_table_id) return 0; } +void physflat_init_apic_ldr(void) +{ + /* LDR is not used in physflat mode. */ +} + static void physflat_send_IPI_allbutself(int vector) { default_send_IPI_mask_allbutself_phys(cpu_online_mask, vector); @@ -251,8 +256,7 @@ static struct apic apic_physflat __ro_after_init = { .dest_logical = 0, .check_apicid_used = NULL, - /* not needed, but shouldn't hurt: */ - .init_apic_ldr = flat_init_apic_ldr, + .init_apic_ldr = physflat_init_apic_ldr, .ioapic_phys_id_map = NULL, .setup_apic_routing = NULL, -- 2.12.3
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