Commit 51130d21 authored by David Woodhouse's avatar David Woodhouse Committed by Thomas Gleixner
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x86/ioapic: Handle Extended Destination ID field in RTE 



Bits 63-48 of the I/OAPIC Redirection Table Entry map directly to bits 19-4
of the address used in the resulting MSI cycle.

Historically, the x86 MSI format only used the top 8 of those 16 bits as
the destination APIC ID, and the "Extended Destination ID" in the lower 8
bits was unused.

With interrupt remapping, the lowest bit of the Extended Destination ID
(bit 48 of RTE, bit 4 of MSI address) is now used to indicate a remappable
format MSI.

A hypervisor can use the other 7 bits of the Extended Destination ID to
permit guests to address up to 15 bits of APIC IDs, thus allowing 32768
vCPUs before having to expose a vIOMMU and interrupt remapping to the
guest.

No behavioural change in this patch, since nothing yet permits APIC IDs
above 255 to be used with the non-IR I/OAPIC domain.

[ tglx: Converted it to the cleaned up entry/msi_msg format and added
  	commentry ]

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201024213535.443185-32-dwmw2@infradead.org
parent 79eb3581

arch/x86/include/asm/io_apic.h

+2 −1
Original line number Diff line number Diff line
@@ -67,7 +67,8 @@ struct IO_APIC_route_entry { 
				is_level		:  1,

				masked			:  1,

				reserved_0		: 15,

				reserved_1		: 24,

				reserved_1		: 17,

				virt_destid_8_14	:  7,

				destid_0_7		:  8;

		};

		struct {

arch/x86/kernel/apic/io_apic.c

+15 −5
Original line number Diff line number Diff line
@@ -1238,9 +1238,10 @@ static void io_apic_print_entries(unsigned int apic, unsigned int nr_entries) 
			       (entry.ir_index_15 << 15) | entry.ir_index_0_14,

				entry.ir_zero);

		} else {

			printk(KERN_DEBUG "%s, %s, D(%02X), M(%1d)\n", buf,

			printk(KERN_DEBUG "%s, %s, D(%02X%02X), M(%1d)\n", buf,

			       entry.dest_mode_logical ? "logical " : "physical",

			       entry.destid_0_7, entry.delivery_mode);

			       entry.virt_destid_8_14, entry.destid_0_7,

			       entry.delivery_mode);

		}

	}

}
@@ -1409,6 +1410,7 @@ void native_restore_boot_irq_mode(void) 
	 */

	if (ioapic_i8259.pin != -1) {

		struct IO_APIC_route_entry entry;

		u32 apic_id = read_apic_id();



		memset(&entry, 0, sizeof(entry));

		entry.masked		= false;
@@ -1416,7 +1418,8 @@ void native_restore_boot_irq_mode(void) 
		entry.active_low	= false;

		entry.dest_mode_logical	= false;

		entry.delivery_mode	= APIC_DELIVERY_MODE_EXTINT;

		entry.destid_0_7	= read_apic_id();

		entry.destid_0_7	= apic_id & 0xFF;

		entry.virt_destid_8_14	= apic_id >> 8;



		/*

		 * Add it to the IO-APIC irq-routing table:
@@ -1885,7 +1888,11 @@ static void ioapic_setup_msg_from_msi(struct irq_data *irq_data, 
	/* DMAR/IR: 1, 0 for all other modes */

	entry->ir_format		= msg.arch_addr_lo.dmar_format;

	/*

	 * DMAR/IR: index bit 0-14.

	 * - DMAR/IR: index bit 0-14.

	 *

	 * - Virt: If the host supports x2apic without a virtualized IR

	 *	   unit then bit 0-6 of dmar_index_0_14 are providing bit

	 *	   8-14 of the destination id.

	 *

	 * All other modes have bit 0-6 of dmar_index_0_14 cleared and the

	 * topmost 8 bits are destination id bit 0-7 (entry::destid_0_7).
@@ -2063,6 +2070,7 @@ static inline void __init unlock_ExtINT_logic(void) 
	int apic, pin, i;

	struct IO_APIC_route_entry entry0, entry1;

	unsigned char save_control, save_freq_select;

	u32 apic_id;



	pin  = find_isa_irq_pin(8, mp_INT);

	if (pin == -1) {
@@ -2078,11 +2086,13 @@ static inline void __init unlock_ExtINT_logic(void) 
	entry0 = ioapic_read_entry(apic, pin);

	clear_IO_APIC_pin(apic, pin);



	apic_id = hard_smp_processor_id();

	memset(&entry1, 0, sizeof(entry1));



	entry1.dest_mode_logical	= true;

	entry1.masked			= false;

	entry1.destid_0_7		= hard_smp_processor_id();

	entry1.destid_0_7		= apic_id & 0xFF;

	entry1.virt_destid_8_14		= apic_id >> 8;

	entry1.delivery_mode		= APIC_DELIVERY_MODE_EXTINT;

	entry1.active_low		= entry0.active_low;

	entry1.is_level			= false;