From 37406aaaeebc36632efc3f493363da9644e57ef1 Mon Sep 17 00:00:00 2001 From: Nadav Har'El Date: Mon, 5 Aug 2013 11:07:12 +0300 Subject: [PATCH] nEPT: Add EPT tables support to paging_tmpl.h This is the first patch in a series which adds nested EPT support to KVM's nested VMX. Nested EPT means emulating EPT for an L1 guest so that L1 can use EPT when running a nested guest L2. When L1 uses EPT, it allows the L2 guest to set its own cr3 and take its own page faults without either of L0 or L1 getting involved. This often significanlty improves L2's performance over the previous two alternatives (shadow page tables over EPT, and shadow page tables over shadow page tables). This patch adds EPT support to paging_tmpl.h. paging_tmpl.h contains the code for reading and writing page tables. The code for 32-bit and 64-bit tables is very similar, but not identical, so paging_tmpl.h is #include'd twice in mmu.c, once with PTTTYPE=32 and once with PTTYPE=64, and this generates the two sets of similar functions. There are subtle but important differences between the format of EPT tables and that of ordinary x86 64-bit page tables, so for nested EPT we need a third set of functions to read the guest EPT table and to write the shadow EPT table. So this patch adds third PTTYPE, PTTYPE_EPT, which creates functions (prefixed with "EPT") which correctly read and write EPT tables. Reviewed-by: Xiao Guangrong Signed-off-by: Nadav Har'El Signed-off-by: Jun Nakajima Signed-off-by: Xinhao Xu Signed-off-by: Yang Zhang Signed-off-by: Gleb Natapov Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu.c | 5 +++++ arch/x86/kvm/paging_tmpl.h | 37 ++++++++++++++++++++++++++++++++++++- 2 files changed, 41 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 6027f8b9d482..2988df5c1e3e 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3494,6 +3494,11 @@ static inline bool is_last_gpte(struct kvm_mmu *mmu, unsigned level, unsigned gp return mmu->last_pte_bitmap & (1 << index); } +#define PTTYPE_EPT 18 /* arbitrary */ +#define PTTYPE PTTYPE_EPT +#include "paging_tmpl.h" +#undef PTTYPE + #define PTTYPE 64 #include "paging_tmpl.h" #undef PTTYPE diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 656f7fae312a..893768825725 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -23,6 +23,13 @@ * so the code in this file is compiled twice, once per pte size. */ +/* + * This is used to catch non optimized PT_GUEST_(DIRTY|ACCESS)_SHIFT macro + * uses for EPT without A/D paging type. + */ +extern u64 __pure __using_nonexistent_pte_bit(void) + __compiletime_error("wrong use of PT_GUEST_(DIRTY|ACCESS)_SHIFT"); + #if PTTYPE == 64 #define pt_element_t u64 #define guest_walker guest_walker64 @@ -58,6 +65,21 @@ #define PT_GUEST_DIRTY_SHIFT PT_DIRTY_SHIFT #define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT #define CMPXCHG cmpxchg +#elif PTTYPE == PTTYPE_EPT + #define pt_element_t u64 + #define guest_walker guest_walkerEPT + #define FNAME(name) ept_##name + #define PT_BASE_ADDR_MASK PT64_BASE_ADDR_MASK + #define PT_LVL_ADDR_MASK(lvl) PT64_LVL_ADDR_MASK(lvl) + #define PT_LVL_OFFSET_MASK(lvl) PT64_LVL_OFFSET_MASK(lvl) + #define PT_INDEX(addr, level) PT64_INDEX(addr, level) + #define PT_LEVEL_BITS PT64_LEVEL_BITS + #define PT_GUEST_ACCESSED_MASK 0 + #define PT_GUEST_DIRTY_MASK 0 + #define PT_GUEST_DIRTY_SHIFT __using_nonexistent_pte_bit() + #define PT_GUEST_ACCESSED_SHIFT __using_nonexistent_pte_bit() + #define CMPXCHG cmpxchg64 + #define PT_MAX_FULL_LEVELS 4 #else #error Invalid PTTYPE value #endif @@ -115,7 +137,11 @@ static bool FNAME(is_rsvd_bits_set)(struct kvm_mmu *mmu, u64 gpte, int level) static inline int FNAME(is_present_gpte)(unsigned long pte) { +#if PTTYPE != PTTYPE_EPT return is_present_gpte(pte); +#else + return pte & 7; +#endif } static int FNAME(cmpxchg_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, @@ -165,9 +191,14 @@ no_present: static inline unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, u64 gpte) { unsigned access; - +#if PTTYPE == PTTYPE_EPT + access = ((gpte & VMX_EPT_WRITABLE_MASK) ? ACC_WRITE_MASK : 0) | + ((gpte & VMX_EPT_EXECUTABLE_MASK) ? ACC_EXEC_MASK : 0) | + ACC_USER_MASK; +#else access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK; access &= ~(gpte >> PT64_NX_SHIFT); +#endif return access; } @@ -369,6 +400,7 @@ static int FNAME(walk_addr)(struct guest_walker *walker, access); } +#if PTTYPE != PTTYPE_EPT static int FNAME(walk_addr_nested)(struct guest_walker *walker, struct kvm_vcpu *vcpu, gva_t addr, u32 access) @@ -376,6 +408,7 @@ static int FNAME(walk_addr_nested)(struct guest_walker *walker, return FNAME(walk_addr_generic)(walker, vcpu, &vcpu->arch.nested_mmu, addr, access); } +#endif static bool FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, @@ -803,6 +836,7 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access, return gpa; } +#if PTTYPE != PTTYPE_EPT static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access, struct x86_exception *exception) @@ -821,6 +855,7 @@ static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gva_t vaddr, return gpa; } +#endif /* * Using the cached information from sp->gfns is safe because: -- 2.39.5