[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 4/6] x86/hvm: Add SMAP support to HVM guest
>>> On 15.04.14 at 15:02, <feng.wu@xxxxxxxxx> wrote: > --- a/xen/arch/x86/mm/guest_walk.c > +++ b/xen/arch/x86/mm/guest_walk.c > @@ -29,6 +29,7 @@ > #include <xen/sched.h> > #include <asm/page.h> > #include <asm/guest_pt.h> > +#include <asm/hvm/vmx/vmx.h> > > > /* Flags that are needed in a pagetable entry, with the sense of NX inverted > */ > @@ -144,14 +145,18 @@ guest_walk_tables(struct vcpu *v, struct p2m_domain > *p2m, > guest_l4e_t *l4p; > #endif > uint32_t gflags, mflags, iflags, rc = 0; > - int smep; > + int smep, smap; These want to be bool_t I suppose. > bool_t pse1G = 0, pse2M = 0; > + unsigned long sel = 0; > + uint64_t eflags = guest_cpu_user_regs()->eflags; > p2m_query_t qt = P2M_ALLOC | P2M_UNSHARE; > > perfc_incr(guest_walk); > memset(gw, 0, sizeof(*gw)); > gw->va = va; > > + __vmread(GUEST_CS_SELECTOR, &sel); You're in common code here - please use the proper HVM abstraction. > @@ -165,7 +170,21 @@ guest_walk_tables(struct vcpu *v, struct p2m_domain *p2m, > * whole walk as if it were a user-mode one and then invert the answer. > */ > smep = (is_hvm_vcpu(v) && hvm_smep_enabled(v) > && (pfec & PFEC_insn_fetch) && !(pfec & PFEC_user_mode) ); > - if ( smep ) > + > + /* > + * SMAP: kernel-mode data accesses from user-mode mappings should fault > + * A fault is considered as a SMAP violation if the following > + * conditions come ture: "true" > + * - X86_CR4_SMAP is set in CR4 > + * - An user page is accessed "A user page ..." afaik. > + * - CPL = 3 or X86_EFLAGS_AC clear set) Stray closing parenthesis. > + * - Page fault in kernel mode > + */ > + smap = ( is_hvm_vcpu(v) && hvm_smap_enabled(v) > + && !(!((sel & 3) == 3) && (eflags & X86_EFLAGS_AC)) !( == ) is better written as ( != ) or, as done elsewhere, ( < ). > + && !(pfec & PFEC_user_mode) ); > + > + if ( smep || smap ) Again, please fold these are far as possible (is_hvm_vcpu() and the PFEC_user_mode are common and hence should be done just once. > @@ -363,6 +365,16 @@ static inline int hvm_event_pending(struct vcpu *v) > #define HVM_CR4_HOST_MASK (mmu_cr4_features & \ > (X86_CR4_VMXE | X86_CR4_PAE | X86_CR4_MCE)) > > +static inline bool_t hvm_cpuid_has_smap(void) > +{ > + unsigned int eax = 0, ebx = 0, ecx = 0, edx = 0; > + unsigned int leaf = 0x7; > + > + hvm_cpuid(leaf, &eax, &ebx, &ecx, &edx); Please pass NULL for all outputs you don't need. > @@ -371,6 +383,7 @@ static inline int hvm_event_pending(struct vcpu *v) > X86_CR4_MCE | X86_CR4_PGE | X86_CR4_PCE | \ > X86_CR4_OSFXSR | X86_CR4_OSXMMEXCPT | \ > (cpu_has_smep ? X86_CR4_SMEP : 0) | \ > + (hvm_cpuid_has_smap() ? X86_CR4_SMAP : 0) | \ What's the reason for the asymmetry with SMEP here? Also, did you verify that v == current in all call paths? And even if you did, passing v into the function and adding a respective ASSERT() would seem rather desirable. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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