Intel new CPU supports SMEP (Supervisor Mode Execution Protection). SMEP
prevents software operating with CPL < 3 (supervisor mode) from fetching
instructions from any linear address with a valid translation for which the U/S
flag (bit 2) is 1 in every paging-structure entry controlling the translation
for the linear address.
This patch adds SMEP support to HVM guest.
Signed-off-by: Yang Wei <wei.y.yang@xxxxxxxxx>
Signed-off-by: Shan Haitao <haitao.shan@xxxxxxxxx>
Signed-off-by: Li Xin <xin.li@xxxxxxxxx>
diff -r 0c0884fd8b49 tools/libxc/xc_cpufeature.h
--- a/tools/libxc/xc_cpufeature.h Fri Jun 03 21:39:00 2011 +0100
+++ b/tools/libxc/xc_cpufeature.h Sun Jun 05 08:07:48 2011 +0800
@@ -124,5 +124,6 @@
/* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx) */
#define X86_FEATURE_FSGSBASE 0 /* {RD,WR}{FS,GS}BASE instructions */
+#define X86_FEATURE_SMEP 7 /* Supervisor Mode Execution Protection */
#endif /* __LIBXC_CPUFEATURE_H */
diff -r 0c0884fd8b49 tools/libxc/xc_cpuid_x86.c
--- a/tools/libxc/xc_cpuid_x86.c Fri Jun 03 21:39:00 2011 +0100
+++ b/tools/libxc/xc_cpuid_x86.c Sun Jun 05 08:07:48 2011 +0800
@@ -351,6 +351,14 @@ static void xc_cpuid_hvm_policy(
clear_bit(X86_FEATURE_PAE, regs[3]);
break;
+ case 0x00000007: /* Intel-defined CPU features */
+ if ( input[1] == 0 ) {
+ regs[1] &= bitmaskof(X86_FEATURE_SMEP);
+ } else
+ regs[1] = 0;
+ regs[0] = regs[2] = regs[3] = 0;
+ break;
+
case 0x0000000d:
xc_cpuid_config_xsave(xch, domid, xfeature_mask, input, regs);
break;
diff -r 0c0884fd8b49 xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c Fri Jun 03 21:39:00 2011 +0100
+++ b/xen/arch/x86/hvm/hvm.c Sun Jun 05 08:07:48 2011 +0800
@@ -1664,7 +1664,8 @@ int hvm_set_cr4(unsigned long value)
hvm_update_guest_cr(v, 4);
/* Modifying CR4.{PSE,PAE,PGE} invalidates all TLB entries, inc. Global. */
- if ( (old_cr ^ value) & (X86_CR4_PSE | X86_CR4_PGE | X86_CR4_PAE) ) {
+ if ( (old_cr ^ value) & (X86_CR4_PSE | X86_CR4_PGE |
+ X86_CR4_PAE | X86_CR4_SMEP) ) {
if ( !nestedhvm_vmswitch_in_progress(v) &&
nestedhvm_vcpu_in_guestmode(v) )
paging_update_nestedmode(v);
else
@@ -2312,7 +2313,8 @@ enum hvm_copy_result hvm_copy_from_guest
enum hvm_copy_result hvm_fetch_from_guest_virt(
void *buf, unsigned long vaddr, int size, uint32_t pfec)
{
- if ( hvm_nx_enabled(current) )
+ if ( hvm_nx_enabled(current) ||
+ (!(pfec | PFEC_user_mode) && hvm_smep_enabled(current)) )
pfec |= PFEC_insn_fetch;
return __hvm_copy(buf, vaddr, size,
HVMCOPY_from_guest | HVMCOPY_fault | HVMCOPY_virt,
@@ -2338,7 +2340,8 @@ enum hvm_copy_result hvm_copy_from_guest
enum hvm_copy_result hvm_fetch_from_guest_virt_nofault(
void *buf, unsigned long vaddr, int size, uint32_t pfec)
{
- if ( hvm_nx_enabled(current) )
+ if ( hvm_nx_enabled(current) ||
+ (!(pfec | PFEC_user_mode) && hvm_smep_enabled(current)) )
pfec |= PFEC_insn_fetch;
return __hvm_copy(buf, vaddr, size,
HVMCOPY_from_guest | HVMCOPY_no_fault | HVMCOPY_virt,
@@ -2408,6 +2411,10 @@ void hvm_cpuid(unsigned int input, unsig
*ecx |= (v->arch.hvm_vcpu.guest_cr[4] & X86_CR4_OSXSAVE) ?
cpufeat_mask(X86_FEATURE_OSXSAVE) : 0;
break;
+ case 0x7:
+ if ( (count == 0) && !cpu_has_smep )
+ *ebx &= ~cpufeat_mask(X86_FEATURE_SMEP);
+ break;
case 0xb:
/* Fix the x2APIC identifier. */
*edx = v->vcpu_id * 2;
diff -r 0c0884fd8b49 xen/arch/x86/mm/guest_walk.c
--- a/xen/arch/x86/mm/guest_walk.c Fri Jun 03 21:39:00 2011 +0100
+++ b/xen/arch/x86/mm/guest_walk.c Sun Jun 05 08:07:48 2011 +0800
@@ -131,7 +131,7 @@ guest_walk_tables(struct vcpu *v, struct
guest_l3e_t *l3p = NULL;
guest_l4e_t *l4p;
#endif
- uint32_t gflags, mflags, iflags, rc = 0;
+ uint32_t gflags, mflags, iflags, user_flag = _PAGE_USER, rc = 0;
int pse;
perfc_incr(guest_walk);
@@ -153,6 +153,7 @@ guest_walk_tables(struct vcpu *v, struct
l4p = (guest_l4e_t *) top_map;
gw->l4e = l4p[guest_l4_table_offset(va)];
gflags = guest_l4e_get_flags(gw->l4e) ^ iflags;
+ user_flag &= gflags;
rc |= ((gflags & mflags) ^ mflags);
if ( rc & _PAGE_PRESENT ) goto out;
@@ -167,6 +168,7 @@ guest_walk_tables(struct vcpu *v, struct
/* Get the l3e and check its flags*/
gw->l3e = l3p[guest_l3_table_offset(va)];
gflags = guest_l3e_get_flags(gw->l3e) ^ iflags;
+ user_flag &= gflags;
rc |= ((gflags & mflags) ^ mflags);
if ( rc & _PAGE_PRESENT )
goto out;
@@ -204,6 +206,7 @@ guest_walk_tables(struct vcpu *v, struct
#endif /* All levels... */
gflags = guest_l2e_get_flags(gw->l2e) ^ iflags;
+ user_flag &= gflags;
rc |= ((gflags & mflags) ^ mflags);
if ( rc & _PAGE_PRESENT )
goto out;
@@ -268,6 +271,7 @@ guest_walk_tables(struct vcpu *v, struct
goto out;
gw->l1e = l1p[guest_l1_table_offset(va)];
gflags = guest_l1e_get_flags(gw->l1e) ^ iflags;
+ user_flag &= gflags;
rc |= ((gflags & mflags) ^ mflags);
}
@@ -277,6 +281,11 @@ guest_walk_tables(struct vcpu *v, struct
* walkers behave this way. */
if ( rc == 0 )
{
+ if ( guest_supports_smep(v) && user_flag &&
+ ((pfec & (PFEC_insn_fetch|PFEC_user_mode)) == PFEC_insn_fetch) ) {
+ rc = _PAGE_SMEP;
+ goto out;
+ }
#if GUEST_PAGING_LEVELS == 4 /* 64-bit only... */
if ( set_ad_bits(l4p + guest_l4_table_offset(va), &gw->l4e, 0) )
paging_mark_dirty(d, mfn_x(gw->l4mfn));
diff -r 0c0884fd8b49 xen/include/asm-x86/guest_pt.h
--- a/xen/include/asm-x86/guest_pt.h Fri Jun 03 21:39:00 2011 +0100
+++ b/xen/include/asm-x86/guest_pt.h Sun Jun 05 08:07:48 2011 +0800
@@ -203,6 +203,13 @@ guest_supports_nx(struct vcpu *v)
return hvm_nx_enabled(v);
}
+static inline int
+guest_supports_smep(struct vcpu *v)
+{
+ if ( !is_hvm_vcpu(v) )
+ return 0;
+ return hvm_smep_enabled(v);
+}
/* Some bits are invalid in any pagetable entry. */
#if GUEST_PAGING_LEVELS == 2
diff -r 0c0884fd8b49 xen/include/asm-x86/hvm/hvm.h
--- a/xen/include/asm-x86/hvm/hvm.h Fri Jun 03 21:39:00 2011 +0100
+++ b/xen/include/asm-x86/hvm/hvm.h Sun Jun 05 08:07:48 2011 +0800
@@ -212,6 +212,8 @@ int hvm_girq_dest_2_vcpu_id(struct domai
(!!((v)->arch.hvm_vcpu.guest_cr[0] & X86_CR0_WP))
#define hvm_pae_enabled(v) \
(hvm_paging_enabled(v) && ((v)->arch.hvm_vcpu.guest_cr[4] & X86_CR4_PAE))
+#define hvm_smep_enabled(v) \
+ (hvm_paging_enabled(v) && ((v)->arch.hvm_vcpu.guest_cr[4] & X86_CR4_SMEP))
#define hvm_nx_enabled(v) \
(!!((v)->arch.hvm_vcpu.guest_efer & EFER_NX))
@@ -321,6 +323,7 @@ static inline int hvm_do_pmu_interrupt(s
X86_CR4_DE | X86_CR4_PSE | X86_CR4_PAE | \
X86_CR4_MCE | X86_CR4_PGE | X86_CR4_PCE | \
X86_CR4_OSFXSR | X86_CR4_OSXMMEXCPT | \
+ (cpu_has_smep ? X86_CR4_SMEP : 0) | \
(xsave_enabled(_v) ? X86_CR4_OSXSAVE : 0))))
/* These exceptions must always be intercepted. */
diff -r 0c0884fd8b49 xen/include/asm-x86/page.h
--- a/xen/include/asm-x86/page.h Fri Jun 03 21:39:00 2011 +0100
+++ b/xen/include/asm-x86/page.h Sun Jun 05 08:07:48 2011 +0800
@@ -326,6 +326,7 @@ void setup_idle_pagetable(void);
#define _PAGE_PSE_PAT 0x1000U
#define _PAGE_PAGED 0x2000U
#define _PAGE_SHARED 0x4000U
+#define _PAGE_SMEP 0x8000U
/*
* Debug option: Ensure that granted mappings are not implicitly unmapped.
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