[Xen-devel] [V2 PATCH 7/9] x86/hvm: pkeys, add pkeys support for guest_walk_tables

[Huaitong Han <huaitong.han@xxxxxxxxx>]

This patch adds pkeys support for guest_walk_tables.

Signed-off-by: Huaitong Han <huaitong.han@xxxxxxxxx>
---
 xen/arch/x86/mm/guest_walk.c  | 65 +++++++++++++++++++++++++++++++++++++++++++
 xen/include/asm-x86/hvm/hvm.h |  2 ++
 2 files changed, 67 insertions(+)

diff --git a/xen/arch/x86/mm/guest_walk.c b/xen/arch/x86/mm/guest_walk.c
index 18d1acf..3e443b3 100644
--- a/xen/arch/x86/mm/guest_walk.c
+++ b/xen/arch/x86/mm/guest_walk.c
@@ -31,6 +31,8 @@ asm(".file \"" __OBJECT_FILE__ "\"");
 #include <xen/sched.h>
 #include <asm/page.h>
 #include <asm/guest_pt.h>
+#include <asm/xstate.h>
+#include <asm/i387.h>
 
 extern const uint32_t gw_page_flags[];
 #if GUEST_PAGING_LEVELS == CONFIG_PAGING_LEVELS
@@ -90,6 +92,53 @@ static uint32_t set_ad_bits(void *guest_p, void *walk_p, int 
set_dirty)
     return 0;
 }
 
+#if GUEST_PAGING_LEVELS >= 4
+uint32_t leaf_pte_pkeys_check(struct vcpu *vcpu, uint32_t pfec,
+                uint32_t pte_access, uint32_t pte_pkeys)
+{
+    bool_t pkru_ad, pkru_wd;
+    bool_t ff, wf, uf, rsvdf, pkuf;
+    unsigned int pkru = 0;
+
+    uf = pfec & PFEC_user_mode;
+    wf = pfec & PFEC_write_access;
+    rsvdf = pfec & PFEC_reserved_bit;
+    ff = pfec & PFEC_insn_fetch;
+    pkuf = pfec & PFEC_prot_key;
+
+    if ( !cpu_has_xsave || !pkuf || is_pv_vcpu(vcpu) )
+        return 0;
+
+    vcpu_save_fpu(vcpu);
+    pkru = *(unsigned int*)get_xsave_addr(vcpu->arch.xsave_area, XSTATE_PKRU);
+    if ( unlikely(pkru) )
+    {
+        /*
+         * PKU:  additional mechanism by which the paging controls
+         * access to user-mode addresses based on the value in the
+         * PKRU register. A fault is considered as a PKU violation if all
+         * of the following conditions are ture:
+         * 1.CR4_PKE=1.
+         * 2.EFER_LMA=1.
+         * 3.page is present with no reserved bit violations.
+         * 4.the access is not an instruction fetch.
+         * 5.the access is to a user page.
+         * 6.PKRU.AD=1
+         *       or The access is a data write and PKRU.WD=1
+         *            and either CR0.WP=1 or it is a user access.
+         */
+        pkru_ad = READ_PKRU_AD(pkru, pte_pkeys);
+        pkru_wd = READ_PKRU_AD(pkru, pte_pkeys);
+        if ( hvm_pku_enabled(vcpu) && hvm_long_mode_enabled(vcpu) &&
+            !rsvdf && !ff && (pkru_ad ||
+            (pkru_wd && wf && (hvm_wp_enabled(vcpu) || uf))))
+            return 1;
+    }
+
+    return 0;
+}
+#endif
+
 /* Walk the guest pagetables, after the manner of a hardware walker. */
 /* Because the walk is essentially random, it can cause a deadlock 
  * warning in the p2m locking code. Highly unlikely this is an actual
@@ -106,6 +155,7 @@ guest_walk_tables(struct vcpu *v, struct p2m_domain *p2m,
 #if GUEST_PAGING_LEVELS >= 4 /* 64-bit only... */
     guest_l3e_t *l3p = NULL;
     guest_l4e_t *l4p;
+    uint32_t pkeys;
 #endif
     uint32_t gflags, mflags, iflags, rc = 0;
     bool_t smep = 0, smap = 0;
@@ -190,6 +240,7 @@ guest_walk_tables(struct vcpu *v, struct p2m_domain *p2m,
         goto out;
     /* Get the l3e and check its flags*/
     gw->l3e = l3p[guest_l3_table_offset(va)];
+    pkeys = guest_l3e_get_pkeys(gw->l3e);
     gflags = guest_l3e_get_flags(gw->l3e) ^ iflags;
     if ( !(gflags & _PAGE_PRESENT) ) {
         rc |= _PAGE_PRESENT;
@@ -199,6 +250,9 @@ guest_walk_tables(struct vcpu *v, struct p2m_domain *p2m,
     
     pse1G = (gflags & _PAGE_PSE) && guest_supports_1G_superpages(v); 
 
+    if (pse1G && leaf_pte_pkeys_check(v, pfec, gflags, pkeys))
+        rc |= _PAGE_PKEY_BIT;
+
     if ( pse1G )
     {
         /* Generate a fake l1 table entry so callers don't all 
@@ -270,6 +324,12 @@ guest_walk_tables(struct vcpu *v, struct p2m_domain *p2m,
 
     pse2M = (gflags & _PAGE_PSE) && guest_supports_superpages(v); 
 
+#if GUEST_PAGING_LEVELS >= 4
+    pkeys = guest_l2e_get_pkeys(gw->l2e);
+    if (pse2M && leaf_pte_pkeys_check(v, pfec, gflags, pkeys))
+        rc |= _PAGE_PKEY_BIT;
+#endif
+
     if ( pse2M )
     {
         /* Special case: this guest VA is in a PSE superpage, so there's
@@ -330,6 +390,11 @@ guest_walk_tables(struct vcpu *v, struct p2m_domain *p2m,
             goto out;
         }
         rc |= ((gflags & mflags) ^ mflags);
+#if GUEST_PAGING_LEVELS >= 4
+        pkeys = guest_l1e_get_pkeys(gw->l1e);
+        if (leaf_pte_pkeys_check(v, pfec, gflags, pkeys))
+            rc |= _PAGE_PKEY_BIT;
+#endif
     }
 
 #if GUEST_PAGING_LEVELS >= 4 /* 64-bit only... */
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index da799a0..cfbb1ef 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -276,6 +276,8 @@ int hvm_girq_dest_2_vcpu_id(struct domain *d, uint8_t dest, 
uint8_t dest_mode);
     (hvm_paging_enabled(v) && ((v)->arch.hvm_vcpu.guest_cr[4] & X86_CR4_SMAP))
 #define hvm_nx_enabled(v) \
     (!!((v)->arch.hvm_vcpu.guest_efer & EFER_NX))
+#define hvm_pku_enabled(v) \
+    (hvm_paging_enabled(v) && ((v)->arch.hvm_vcpu.guest_cr[4] & X86_CR4_PKE))
 
 /* Can we use superpages in the HAP p2m table? */
 #define hap_has_1gb (!!(hvm_funcs.hap_capabilities & HVM_HAP_SUPERPAGE_1GB))
-- 
2.4.3


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