| Message ID | 1369444359-28962-1-git-send-email-cdall@cs.columbia.edu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 24 May 2013 18:12:39 -0700, Christoffer Dall <cdall@cs.columbia.edu> wrote: > THe L_PTE_USER actually has nothing to do with stage 2 mappings and the > L_PTE_S2_RDWR value sets the readable bit, which was what L_PTE_USER > was used for before proper handling of stage 2 memory defines. > > Changelog: > [v2]: Change default mappings to be r/w instead of r/o, as per Marc > Zyngier's suggestion. > > Cc: Marc Zyngier <marc.zyngier@arm.com> > Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu> > --- > arch/arm/include/asm/pgtable.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/include/asm/pgtable.h > b/arch/arm/include/asm/pgtable.h > index 9bcd262..8afc60c 100644 > --- a/arch/arm/include/asm/pgtable.h > +++ b/arch/arm/include/asm/pgtable.h > @@ -97,7 +97,7 @@ extern pgprot_t pgprot_s2_device; > #define PAGE_HYP _MOD_PROT(pgprot_kernel, L_PTE_HYP) > #define PAGE_HYP_DEVICE _MOD_PROT(pgprot_hyp_device, L_PTE_HYP) > #define PAGE_S2 _MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY) > -#define PAGE_S2_DEVICE _MOD_PROT(pgprot_s2_device, L_PTE_USER | > L_PTE_S2_RDONLY) > +#define PAGE_S2_DEVICE _MOD_PROT(pgprot_s2_device, L_PTE_S2_RDWR) > > #define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN | > L_PTE_NONE) > #define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN) Actually, there's a much better solution. Just get rid of PAGE_S2_DEVICE altogether, as it is completely useless. We never have to enforce a memory type in S2 that is stronger than the guest's view. If the guest insists on doing something silly (mapping a device as normal memory, for example), we really don't have to fix things for them. See the patch I posted a while ago as part of my pending fixes series: https://lists.cs.columbia.edu/pipermail/kvmarm/2013-May/005827.html M.
On Sat, May 25, 2013 at 3:02 AM, Marc Zyngier <maz@misterjones.org> wrote: > On Fri, 24 May 2013 18:12:39 -0700, Christoffer Dall > <cdall@cs.columbia.edu> wrote: >> THe L_PTE_USER actually has nothing to do with stage 2 mappings and the >> L_PTE_S2_RDWR value sets the readable bit, which was what L_PTE_USER >> was used for before proper handling of stage 2 memory defines. >> >> Changelog: >> [v2]: Change default mappings to be r/w instead of r/o, as per Marc >> Zyngier's suggestion. >> >> Cc: Marc Zyngier <marc.zyngier@arm.com> >> Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu> >> --- >> arch/arm/include/asm/pgtable.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm/include/asm/pgtable.h >> b/arch/arm/include/asm/pgtable.h >> index 9bcd262..8afc60c 100644 >> --- a/arch/arm/include/asm/pgtable.h >> +++ b/arch/arm/include/asm/pgtable.h >> @@ -97,7 +97,7 @@ extern pgprot_t pgprot_s2_device; >> #define PAGE_HYP _MOD_PROT(pgprot_kernel, L_PTE_HYP) >> #define PAGE_HYP_DEVICE _MOD_PROT(pgprot_hyp_device, L_PTE_HYP) >> #define PAGE_S2 _MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY) >> -#define PAGE_S2_DEVICE _MOD_PROT(pgprot_s2_device, L_PTE_USER | >> L_PTE_S2_RDONLY) >> +#define PAGE_S2_DEVICE _MOD_PROT(pgprot_s2_device, L_PTE_S2_RDWR) >> >> #define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN > | >> L_PTE_NONE) >> #define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN) > > Actually, there's a much better solution. > > Just get rid of PAGE_S2_DEVICE altogether, as it is completely useless. We > never have to enforce a memory type in S2 that is stronger than the guest's > view. If the guest insists on doing something silly (mapping a device as > normal memory, for example), we really don't have to fix things for them. > > See the patch I posted a while ago as part of my pending fixes series: > https://lists.cs.columbia.edu/pipermail/kvmarm/2013-May/005827.html > yeah duh, I'll reply to that one.
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index 9bcd262..8afc60c 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -97,7 +97,7 @@ extern pgprot_t pgprot_s2_device; #define PAGE_HYP _MOD_PROT(pgprot_kernel, L_PTE_HYP) #define PAGE_HYP_DEVICE _MOD_PROT(pgprot_hyp_device, L_PTE_HYP) #define PAGE_S2 _MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY) -#define PAGE_S2_DEVICE _MOD_PROT(pgprot_s2_device, L_PTE_USER | L_PTE_S2_RDONLY) +#define PAGE_S2_DEVICE _MOD_PROT(pgprot_s2_device, L_PTE_S2_RDWR) #define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN | L_PTE_NONE) #define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN)
THe L_PTE_USER actually has nothing to do with stage 2 mappings and the L_PTE_S2_RDWR value sets the readable bit, which was what L_PTE_USER was used for before proper handling of stage 2 memory defines. Changelog: [v2]: Change default mappings to be r/w instead of r/o, as per Marc Zyngier's suggestion. Cc: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu> --- arch/arm/include/asm/pgtable.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)