diff options
Diffstat (limited to 'arch/x86/lguest')
| -rw-r--r-- | arch/x86/lguest/boot.c | 36 | ||||
| -rw-r--r-- | arch/x86/lguest/i386_head.S | 35 |
2 files changed, 42 insertions, 29 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index db832fd..13ee258 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -71,7 +71,8 @@ #include <asm/stackprotector.h> #include <asm/reboot.h> /* for struct machine_ops */ -/*G:010 Welcome to the Guest! +/*G:010 + * Welcome to the Guest! * * The Guest in our tale is a simple creature: identical to the Host but * behaving in simplified but equivalent ways. In particular, the Guest is the @@ -190,15 +191,23 @@ static void lazy_hcall4(unsigned long call, #endif /*G:036 - * When lazy mode is turned off reset the per-cpu lazy mode variable and then - * issue the do-nothing hypercall to flush any stored calls. -:*/ + * When lazy mode is turned off, we issue the do-nothing hypercall to + * flush any stored calls, and call the generic helper to reset the + * per-cpu lazy mode variable. + */ static void lguest_leave_lazy_mmu_mode(void) { hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0); paravirt_leave_lazy_mmu(); } +/* + * We also catch the end of context switch; we enter lazy mode for much of + * that too, so again we need to flush here. + * + * (Technically, this is lazy CPU mode, and normally we're in lazy MMU + * mode, but unlike Xen, lguest doesn't care about the difference). + */ static void lguest_end_context_switch(struct task_struct *next) { hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0); @@ -391,7 +400,7 @@ static void lguest_load_tr_desc(void) * giant ball of hair. Its entry in the current Intel manual runs to 28 pages. * * This instruction even it has its own Wikipedia entry. The Wikipedia entry - * has been translated into 5 languages. I am not making this up! + * has been translated into 6 languages. I am not making this up! * * We could get funky here and identify ourselves as "GenuineLguest", but * instead we just use the real "cpuid" instruction. Then I pretty much turned @@ -458,7 +467,7 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx, /* * PAE systems can mark pages as non-executable. Linux calls this the * NX bit. Intel calls it XD (eXecute Disable), AMD EVP (Enhanced - * Virus Protection). We just switch turn if off here, since we don't + * Virus Protection). We just switch it off here, since we don't * support it. */ case 0x80000001: @@ -520,17 +529,16 @@ static unsigned long lguest_read_cr2(void) /* See lguest_set_pte() below. */ static bool cr3_changed = false; +static unsigned long current_cr3; /* * cr3 is the current toplevel pagetable page: the principle is the same as - * cr0. Keep a local copy, and tell the Host when it changes. The only - * difference is that our local copy is in lguest_data because the Host needs - * to set it upon our initial hypercall. + * cr0. Keep a local copy, and tell the Host when it changes. */ static void lguest_write_cr3(unsigned long cr3) { - lguest_data.pgdir = cr3; lazy_hcall1(LHCALL_NEW_PGTABLE, cr3); + current_cr3 = cr3; /* These two page tables are simple, linear, and used during boot */ if (cr3 != __pa(swapper_pg_dir) && cr3 != __pa(initial_page_table)) @@ -539,7 +547,7 @@ static void lguest_write_cr3(unsigned long cr3) static unsigned long lguest_read_cr3(void) { - return lguest_data.pgdir; + return current_cr3; } /* cr4 is used to enable and disable PGE, but we don't care. */ @@ -641,7 +649,7 @@ static void lguest_write_cr4(unsigned long val) /* * The Guest calls this after it has set a second-level entry (pte), ie. to map - * a page into a process' address space. Wetell the Host the toplevel and + * a page into a process' address space. We tell the Host the toplevel and * address this corresponds to. The Guest uses one pagetable per process, so * we need to tell the Host which one we're changing (mm->pgd). */ @@ -758,7 +766,7 @@ static void lguest_pmd_clear(pmd_t *pmdp) static void lguest_flush_tlb_single(unsigned long addr) { /* Simply set it to zero: if it was not, it will fault back in. */ - lazy_hcall3(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0); + lazy_hcall3(LHCALL_SET_PTE, current_cr3, addr, 0); } /* @@ -1140,7 +1148,7 @@ static struct notifier_block paniced = { static __init char *lguest_memory_setup(void) { /* - *The Linux bootloader header contains an "e820" memory map: the + * The Linux bootloader header contains an "e820" memory map: the * Launcher populated the first entry with our memory limit. */ e820_add_region(boot_params.e820_map[0].addr, diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S index 4f420c2f..6ddfe4f 100644 --- a/arch/x86/lguest/i386_head.S +++ b/arch/x86/lguest/i386_head.S @@ -6,18 +6,22 @@ #include <asm/processor-flags.h> /*G:020 - * Our story starts with the kernel booting into startup_32 in - * arch/x86/kernel/head_32.S. It expects a boot header, which is created by - * the bootloader (the Launcher in our case). + + * Our story starts with the bzImage: booting starts at startup_32 in + * arch/x86/boot/compressed/head_32.S. This merely uncompresses the real + * kernel in place and then jumps into it: startup_32 in + * arch/x86/kernel/head_32.S. Both routines expects a boot header in the %esi + * register, which is created by the bootloader (the Launcher in our case). * * The startup_32 function does very little: it clears the uninitialized global * C variables which we expect to be zero (ie. BSS) and then copies the boot - * header and kernel command line somewhere safe. Finally it checks the - * 'hardware_subarch' field. This was introduced in 2.6.24 for lguest and Xen: - * if it's set to '1' (lguest's assigned number), then it calls us here. + * header and kernel command line somewhere safe, and populates some initial + * page tables. Finally it checks the 'hardware_subarch' field. This was + * introduced in 2.6.24 for lguest and Xen: if it's set to '1' (lguest's + * assigned number), then it calls us here. * * WARNING: be very careful here! We're running at addresses equal to physical - * addesses (around 0), not above PAGE_OFFSET as most code expectes + * addresses (around 0), not above PAGE_OFFSET as most code expects * (eg. 0xC0000000). Jumps are relative, so they're OK, but we can't touch any * data without remembering to subtract __PAGE_OFFSET! * @@ -27,13 +31,18 @@ .section .init.text, "ax", @progbits ENTRY(lguest_entry) /* - * We make the "initialization" hypercall now to tell the Host about - * us, and also find out where it put our page tables. + * We make the "initialization" hypercall now to tell the Host where + * our lguest_data struct is. */ movl $LHCALL_LGUEST_INIT, %eax movl $lguest_data - __PAGE_OFFSET, %ebx int $LGUEST_TRAP_ENTRY + /* Now turn our pagetables on; setup by arch/x86/kernel/head_32.S. */ + movl $LHCALL_NEW_PGTABLE, %eax + movl $(initial_page_table - __PAGE_OFFSET), %ebx + int $LGUEST_TRAP_ENTRY + /* Set up the initial stack so we can run C code. */ movl $(init_thread_union+THREAD_SIZE),%esp @@ -96,12 +105,8 @@ send_interrupts: */ pushl %eax movl $LHCALL_SEND_INTERRUPTS, %eax - /* - * This is a vmcall instruction (same thing that KVM uses). Older - * assembler versions might not know the "vmcall" instruction, so we - * create one manually here. - */ - .byte 0x0f,0x01,0xc1 /* KVM_HYPERCALL */ + /* This is the actual hypercall trap. */ + int $LGUEST_TRAP_ENTRY /* Put eax back the way we found it. */ popl %eax ret |
