From a67f913d6635772af746fc215066e3d510ae25d1 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Fri, 15 Mar 2024 13:12:22 +0000 Subject: [librm] Add support for installing a startup IPI handler Application processors are started via INIT and SIPI interprocessor interrupts: the INIT places the processor into a "wait for SIPI" state, and the SIPI then starts the processor in real mode at a page-aligned address derived from the SIPI vector number. Add support for installing a real-mode SIPI handler that will switch the CPU into protected mode with flat physical addressing, load initial register contents, and then jump to the address of a protected-mode SIPI handler. No stack pointer is set up, to avoid the need to allocate stack space for each available processor. We use 32-bit physical addressing in order to minimise the changes required for a 64-bit build. The existing long mode transition code relies on the existence of the stack, so we cannot easily switch the application processor into long mode. We could use 32-bit virtual addressing, but this runtime environment does not currently exist outside of librm.S itself in a 64-bit build, and using it would complicate the implementation of the protected-mode SIPI handler. Signed-off-by: Michael Brown --- src/arch/x86/transitions/librm_mgmt.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'src/arch/x86/transitions/librm_mgmt.c') diff --git a/src/arch/x86/transitions/librm_mgmt.c b/src/arch/x86/transitions/librm_mgmt.c index da221e8b..b3820589 100644 --- a/src/arch/x86/transitions/librm_mgmt.c +++ b/src/arch/x86/transitions/librm_mgmt.c @@ -45,6 +45,9 @@ struct idtr64 idtr64 = { .limit = ( sizeof ( idt64 ) - 1 ), }; +/** Startup IPI register state */ +struct i386_regs sipi_regs; + /** Length of stack dump */ #define STACK_DUMP_LEN 128 @@ -402,6 +405,29 @@ __asmcall void check_fxsr ( struct i386_all_regs *regs ) { ( ( regs->flags & CF ) ? " not" : "" ) ); } +/** + * Set up startup IPI handler + * + * @v vector Startup IPI vector + * @v handler Protected-mode startup IPI handler physical address + * @v regs Initial register state + */ +void setup_sipi ( unsigned int vector, uint32_t handler, + struct i386_regs *regs ) { + + /* Record protected-mode handler */ + sipi_handler = handler; + + /* Update copy of rm_ds */ + sipi_ds = rm_ds; + + /* Save register state */ + memcpy ( &sipi_regs, regs, sizeof ( sipi_regs ) ); + + /* Copy real-mode handler */ + copy_to_real ( ( vector << 8 ), 0, sipi, ( ( size_t ) sipi_len ) ); +} + PROVIDE_UACCESS_INLINE ( librm, phys_to_user ); PROVIDE_UACCESS_INLINE ( librm, user_to_phys ); PROVIDE_UACCESS_INLINE ( librm, virt_to_user ); -- cgit v1.2.3-55-g7522