diff options
| -rw-r--r-- | arch/x86/lguest/boot.c | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index 48ee4f9..4e22fa0 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, * lazily after a task switch, and Linux uses that gratefully, but wouldn't a * name like "FPUTRAP bit" be a little less cryptic? * - * We store cr0 (and cr3) locally, because the Host never changes it. The - * Guest sometimes wants to read it and we'd prefer not to bother the Host - * unnecessarily. */ -static unsigned long current_cr0, current_cr3; + * We store cr0 locally because the Host never changes it. The Guest sometimes + * wants to read it and we'd prefer not to bother the Host unnecessarily. */ +static unsigned long current_cr0; static void lguest_write_cr0(unsigned long val) { lazy_hcall(LHCALL_TS, val & X86_CR0_TS, 0, 0); @@ -399,17 +398,23 @@ static unsigned long lguest_read_cr2(void) return lguest_data.cr2; } +/* See lguest_set_pte() below. */ +static bool cr3_changed = false; + /* 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. */ + * 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. */ static void lguest_write_cr3(unsigned long cr3) { + lguest_data.pgdir = cr3; lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0); - current_cr3 = cr3; + cr3_changed = true; } static unsigned long lguest_read_cr3(void) { - return current_cr3; + return lguest_data.pgdir; } /* 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) * to forget all of them. Fortunately, this is very rare. * * ... except in early boot when the kernel sets up the initial pagetables, - * which makes booting astonishingly slow. So we don't even tell the Host - * anything changed until we've done the first page table switch. */ + * which makes booting astonishingly slow: 1.83 seconds! So we don't even tell + * the Host anything changed until we've done the first page table switch, + * which brings boot back to 0.25 seconds. */ static void lguest_set_pte(pte_t *ptep, pte_t pteval) { *ptep = pteval; - /* Don't bother with hypercall before initial setup. */ - if (current_cr3) + if (cr3_changed) lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0); } @@ -521,7 +526,7 @@ static void lguest_set_pte(pte_t *ptep, pte_t pteval) static void lguest_flush_tlb_single(unsigned long addr) { /* Simply set it to zero: if it was not, it will fault back in. */ - lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0); + lazy_hcall(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0); } /* This is what happens after the Guest has removed a large number of entries. |
