lkml.org 
[lkml]   [2012]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 4/9] KVM: MMU: introduce SPTE_ALLOW_WRITE bit
On Fri, Apr 20, 2012 at 04:18:47PM +0800, Xiao Guangrong wrote:
> This bit indicates whether the spte is allow to be writable that
> means the gpte of this spte is writable and the pfn pointed by
> this spte is writable on host
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
> ---
> arch/x86/kvm/mmu.c | 13 ++++++-------
> 1 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index e70ff38..dd984b6 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -145,7 +145,8 @@ module_param(dbg, bool, 0644);
> #define CREATE_TRACE_POINTS
> #include "mmutrace.h"
>
> -#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
> +#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
> +#define SPTE_ALLOW_WRITE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))
>
> #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
>
> @@ -1177,9 +1178,8 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
> new_spte = *sptep & ~PT64_BASE_ADDR_MASK;
> new_spte |= (u64)new_pfn << PAGE_SHIFT;
>
> - new_spte &= ~PT_WRITABLE_MASK;
> - new_spte &= ~SPTE_HOST_WRITEABLE;
> - new_spte &= ~shadow_accessed_mask;
> + new_spte &= ~(PT_WRITABLE_MASK | SPTE_HOST_WRITEABLE |
> + shadow_accessed_mask | SPTE_ALLOW_WRITE);

Each bit should have a distinct meaning. Here the host pte is being
write-protected, which means only the SPTE_HOST_WRITEABLE bit
should be cleared.


\
 
 \ /
  Last update: 2012-04-21 02:15    [W:0.149 / U:0.532 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site