| Message ID | 1364909115-3810-3-git-send-email-marc.zyngier@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 02, 2013 at 02:25:10PM +0100, Marc Zyngier wrote: > The current code for creating HYP mapping doesn't like to wrap > around zero, which prevents from mapping anything into the last > page of the virtual address space. > > It doesn't take much effort to remove this limitation, making > the code more consistent with the rest of the kernel in the process. This is quite funny, the code used to behave like this, but reviewers said that this was old fashioned mm-style code that was unwanted and wrapping around zero should be avoided for all costs :) In any case, I welcome the familiarity. -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 04/04/13 00:14, Christoffer Dall wrote: > On Tue, Apr 02, 2013 at 02:25:10PM +0100, Marc Zyngier wrote: >> The current code for creating HYP mapping doesn't like to wrap >> around zero, which prevents from mapping anything into the last >> page of the virtual address space. >> >> It doesn't take much effort to remove this limitation, making >> the code more consistent with the rest of the kernel in the process. > > This is quite funny, the code used to behave like this, but > reviewers said that this was old fashioned mm-style code that was > unwanted and wrapping around zero should be avoided for all costs :) My original attempt at this series was using the very last page of the memory, and it took me a while to notice that the code couldn't map anything in the last page. Just for this reason, the code needed to be fixed. > In any case, I welcome the familiarity. Amen. M.
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 24811d1..eb4f8fa 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -131,11 +131,12 @@ static void create_hyp_pte_mappings(pmd_t *pmd, unsigned long start, pte_t *pte; unsigned long addr; - for (addr = start; addr < end; addr += PAGE_SIZE) { + addr = start; + do { pte = pte_offset_kernel(pmd, addr); kvm_set_pte(pte, pfn_pte(pfn, prot)); pfn++; - } + } while (addr += PAGE_SIZE, addr != end); } static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start, @@ -146,7 +147,8 @@ static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start, pte_t *pte; unsigned long addr, next; - for (addr = start; addr < end; addr = next) { + addr = start; + do { pmd = pmd_offset(pud, addr); BUG_ON(pmd_sect(*pmd)); @@ -164,7 +166,7 @@ static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start, create_hyp_pte_mappings(pmd, addr, next, pfn, prot); pfn += (next - addr) >> PAGE_SHIFT; - } + } while (addr = next, addr != end); return 0; } @@ -179,11 +181,10 @@ static int __create_hyp_mappings(pgd_t *pgdp, unsigned long addr, next; int err = 0; - if (start >= end) - return -EINVAL; - mutex_lock(&kvm_hyp_pgd_mutex); - for (addr = start & PAGE_MASK; addr < end; addr = next) { + addr = start & PAGE_MASK; + end = PAGE_ALIGN(end); + do { pgd = pgdp + pgd_index(addr); pud = pud_offset(pgd, addr); @@ -202,7 +203,7 @@ static int __create_hyp_mappings(pgd_t *pgdp, if (err) goto out; pfn += (next - addr) >> PAGE_SHIFT; - } + } while (addr = next, addr != end); out: mutex_unlock(&kvm_hyp_pgd_mutex); return err; @@ -216,8 +217,6 @@ out: * The same virtual address as the kernel virtual address is also used * in Hyp-mode mapping (modulo HYP_PAGE_OFFSET) to the same underlying * physical pages. - * - * Note: Wrapping around zero in the "to" address is not supported. */ int create_hyp_mappings(void *from, void *to) {
The current code for creating HYP mapping doesn't like to wrap around zero, which prevents from mapping anything into the last page of the virtual address space. It doesn't take much effort to remove this limitation, making the code more consistent with the rest of the kernel in the process. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm/kvm/mmu.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-)