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authorRusty Russell <rusty@rustcorp.com.au>2008-10-31 12:24:27 -0400
committerRusty Russell <rusty@rustcorp.com.au>2008-10-30 20:24:27 -0400
commitad5173ff8a387191dbacf889becb92c59aba5d59 (patch)
treebf8af6cb614593de091312bd7fa3c53ba6704e38 /arch/x86/lguest
parentd5d02d6dd394b295abcadd6b0ce4932c07916fdf (diff)
lguest: fix early_ioremap.
dmi_scan_machine breaks under lguest: lguest: unhandled trap 14 at 0xc04edeae (0xffa00000) This is because we use current_cr3 for the read_cr3() paravirt function, and it isn't set until the first cr3 change. We got away with it until this happened. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'arch/x86/lguest')
-rw-r--r--arch/x86/lguest/boot.c29
1 files changed, 17 insertions, 12 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 48ee4f9435f4..4e22fa08d629 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -367,10 +367,9 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
367 * lazily after a task switch, and Linux uses that gratefully, but wouldn't a 367 * lazily after a task switch, and Linux uses that gratefully, but wouldn't a
368 * name like "FPUTRAP bit" be a little less cryptic? 368 * name like "FPUTRAP bit" be a little less cryptic?
369 * 369 *
370 * We store cr0 (and cr3) locally, because the Host never changes it. The 370 * We store cr0 locally because the Host never changes it. The Guest sometimes
371 * Guest sometimes wants to read it and we'd prefer not to bother the Host 371 * wants to read it and we'd prefer not to bother the Host unnecessarily. */
372 * unnecessarily. */ 372static unsigned long current_cr0;
373static unsigned long current_cr0, current_cr3;
374static void lguest_write_cr0(unsigned long val) 373static void lguest_write_cr0(unsigned long val)
375{ 374{
376 lazy_hcall(LHCALL_TS, val & X86_CR0_TS, 0, 0); 375 lazy_hcall(LHCALL_TS, val & X86_CR0_TS, 0, 0);
@@ -399,17 +398,23 @@ static unsigned long lguest_read_cr2(void)
399 return lguest_data.cr2; 398 return lguest_data.cr2;
400} 399}
401 400
401/* See lguest_set_pte() below. */
402static bool cr3_changed = false;
403
402/* cr3 is the current toplevel pagetable page: the principle is the same as 404/* cr3 is the current toplevel pagetable page: the principle is the same as
403 * cr0. Keep a local copy, and tell the Host when it changes. */ 405 * cr0. Keep a local copy, and tell the Host when it changes. The only
406 * difference is that our local copy is in lguest_data because the Host needs
407 * to set it upon our initial hypercall. */
404static void lguest_write_cr3(unsigned long cr3) 408static void lguest_write_cr3(unsigned long cr3)
405{ 409{
410 lguest_data.pgdir = cr3;
406 lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0); 411 lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
407 current_cr3 = cr3; 412 cr3_changed = true;
408} 413}
409 414
410static unsigned long lguest_read_cr3(void) 415static unsigned long lguest_read_cr3(void)
411{ 416{
412 return current_cr3; 417 return lguest_data.pgdir;
413} 418}
414 419
415/* cr4 is used to enable and disable PGE, but we don't care. */ 420/* cr4 is used to enable and disable PGE, but we don't care. */
@@ -498,13 +503,13 @@ static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
498 * to forget all of them. Fortunately, this is very rare. 503 * to forget all of them. Fortunately, this is very rare.
499 * 504 *
500 * ... except in early boot when the kernel sets up the initial pagetables, 505 * ... except in early boot when the kernel sets up the initial pagetables,
501 * which makes booting astonishingly slow. So we don't even tell the Host 506 * which makes booting astonishingly slow: 1.83 seconds! So we don't even tell
502 * anything changed until we've done the first page table switch. */ 507 * the Host anything changed until we've done the first page table switch,
508 * which brings boot back to 0.25 seconds. */
503static void lguest_set_pte(pte_t *ptep, pte_t pteval) 509static void lguest_set_pte(pte_t *ptep, pte_t pteval)
504{ 510{
505 *ptep = pteval; 511 *ptep = pteval;
506 /* Don't bother with hypercall before initial setup. */ 512 if (cr3_changed)
507 if (current_cr3)
508 lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0); 513 lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
509} 514}
510 515
@@ -521,7 +526,7 @@ static void lguest_set_pte(pte_t *ptep, pte_t pteval)
521static void lguest_flush_tlb_single(unsigned long addr) 526static void lguest_flush_tlb_single(unsigned long addr)
522{ 527{
523 /* Simply set it to zero: if it was not, it will fault back in. */ 528 /* Simply set it to zero: if it was not, it will fault back in. */
524 lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0); 529 lazy_hcall(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0);
525} 530}
526 531
527/* This is what happens after the Guest has removed a large number of entries. 532/* This is what happens after the Guest has removed a large number of entries.