From: Avi Kivity <avi@qumranet.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 48/50] KVM: x86 emulator: lazily evaluate segment registers
Date: Thu, 26 Jun 2008 15:28:30 +0300 [thread overview]
Message-ID: <1214483312-9265-49-git-send-email-avi@qumranet.com> (raw)
In-Reply-To: <1214483312-9265-1-git-send-email-avi@qumranet.com>
Instead of prefetching all segment bases before emulation, read them at the
last moment. Since most of them are unneeded, we save some cycles on
Intel machines where this is a bit expensive.
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
arch/x86/kvm/x86.c | 21 --------
arch/x86/kvm/x86_emulate.c | 96 ++++++++++++++++++++++---------------
include/asm-x86/kvm_x86_emulate.h | 10 +---
3 files changed, 60 insertions(+), 67 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ccb4e1e..0fbc032 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2126,27 +2126,6 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
? X86EMUL_MODE_PROT64 : cs_db
? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;
- if (vcpu->arch.emulate_ctxt.mode == X86EMUL_MODE_PROT64) {
- vcpu->arch.emulate_ctxt.cs_base = 0;
- vcpu->arch.emulate_ctxt.ds_base = 0;
- vcpu->arch.emulate_ctxt.es_base = 0;
- vcpu->arch.emulate_ctxt.ss_base = 0;
- } else {
- vcpu->arch.emulate_ctxt.cs_base =
- get_segment_base(vcpu, VCPU_SREG_CS);
- vcpu->arch.emulate_ctxt.ds_base =
- get_segment_base(vcpu, VCPU_SREG_DS);
- vcpu->arch.emulate_ctxt.es_base =
- get_segment_base(vcpu, VCPU_SREG_ES);
- vcpu->arch.emulate_ctxt.ss_base =
- get_segment_base(vcpu, VCPU_SREG_SS);
- }
-
- vcpu->arch.emulate_ctxt.gs_base =
- get_segment_base(vcpu, VCPU_SREG_GS);
- vcpu->arch.emulate_ctxt.fs_base =
- get_segment_base(vcpu, VCPU_SREG_FS);
-
r = x86_decode_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);
/* Reject the instructions other than VMCALL/VMMCALL when
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 38926b7..18ca25c 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -522,6 +522,39 @@ static inline void jmp_rel(struct decode_cache *c, int rel)
register_address_increment(c, &c->eip, rel);
}
+static void set_seg_override(struct decode_cache *c, int seg)
+{
+ c->has_seg_override = true;
+ c->seg_override = seg;
+}
+
+static unsigned long seg_base(struct x86_emulate_ctxt *ctxt, int seg)
+{
+ if (ctxt->mode == X86EMUL_MODE_PROT64 && seg < VCPU_SREG_FS)
+ return 0;
+
+ return kvm_x86_ops->get_segment_base(ctxt->vcpu, seg);
+}
+
+static unsigned long seg_override_base(struct x86_emulate_ctxt *ctxt,
+ struct decode_cache *c)
+{
+ if (!c->has_seg_override)
+ return 0;
+
+ return seg_base(ctxt, c->seg_override);
+}
+
+static unsigned long es_base(struct x86_emulate_ctxt *ctxt)
+{
+ return seg_base(ctxt, VCPU_SREG_ES);
+}
+
+static unsigned long ss_base(struct x86_emulate_ctxt *ctxt)
+{
+ return seg_base(ctxt, VCPU_SREG_SS);
+}
+
static int do_fetch_insn_byte(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops,
unsigned long linear, u8 *dest)
@@ -735,8 +768,8 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
}
if (c->modrm_rm == 2 || c->modrm_rm == 3 ||
(c->modrm_rm == 6 && c->modrm_mod != 0))
- if (!c->override_base)
- c->override_base = &ctxt->ss_base;
+ if (!c->has_seg_override)
+ set_seg_override(c, VCPU_SREG_SS);
c->modrm_ea = (u16)c->modrm_ea;
} else {
/* 32/64-bit ModR/M decode. */
@@ -807,6 +840,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
memset(c, 0, sizeof(struct decode_cache));
c->eip = ctxt->vcpu->arch.rip;
+ ctxt->cs_base = seg_base(ctxt, VCPU_SREG_CS);
memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);
switch (mode) {
@@ -845,23 +879,15 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
/* switch between 2/4 bytes */
c->ad_bytes = def_ad_bytes ^ 6;
break;
+ case 0x26: /* ES override */
case 0x2e: /* CS override */
- c->override_base = &ctxt->cs_base;
- break;
+ case 0x36: /* SS override */
case 0x3e: /* DS override */
- c->override_base = &ctxt->ds_base;
- break;
- case 0x26: /* ES override */
- c->override_base = &ctxt->es_base;
+ set_seg_override(c, (c->b >> 3) & 3);
break;
case 0x64: /* FS override */
- c->override_base = &ctxt->fs_base;
- break;
case 0x65: /* GS override */
- c->override_base = &ctxt->gs_base;
- break;
- case 0x36: /* SS override */
- c->override_base = &ctxt->ss_base;
+ set_seg_override(c, c->b & 7);
break;
case 0x40 ... 0x4f: /* REX */
if (mode != X86EMUL_MODE_PROT64)
@@ -933,15 +959,11 @@ done_prefixes:
if (rc)
goto done;
- if (!c->override_base)
- c->override_base = &ctxt->ds_base;
- if (mode == X86EMUL_MODE_PROT64 &&
- c->override_base != &ctxt->fs_base &&
- c->override_base != &ctxt->gs_base)
- c->override_base = NULL;
+ if (!c->has_seg_override)
+ set_seg_override(c, VCPU_SREG_DS);
- if (c->override_base && !(!c->twobyte && c->b == 0x8d))
- c->modrm_ea += *c->override_base;
+ if (!(!c->twobyte && c->b == 0x8d))
+ c->modrm_ea += seg_override_base(ctxt, c);
if (c->ad_bytes != 8)
c->modrm_ea = (u32)c->modrm_ea;
@@ -1043,7 +1065,7 @@ static inline void emulate_push(struct x86_emulate_ctxt *ctxt)
c->dst.bytes = c->op_bytes;
c->dst.val = c->src.val;
register_address_increment(c, &c->regs[VCPU_REGS_RSP], -c->op_bytes);
- c->dst.ptr = (void *) register_address(c, ctxt->ss_base,
+ c->dst.ptr = (void *) register_address(c, ss_base(ctxt),
c->regs[VCPU_REGS_RSP]);
}
@@ -1053,7 +1075,7 @@ static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
struct decode_cache *c = &ctxt->decode;
int rc;
- rc = ops->read_std(register_address(c, ctxt->ss_base,
+ rc = ops->read_std(register_address(c, ss_base(ctxt),
c->regs[VCPU_REGS_RSP]),
&c->dst.val, c->dst.bytes, ctxt->vcpu);
if (rc != 0)
@@ -1375,11 +1397,11 @@ special_insn:
register_address_increment(c, &c->regs[VCPU_REGS_RSP],
-c->op_bytes);
c->dst.ptr = (void *) register_address(
- c, ctxt->ss_base, c->regs[VCPU_REGS_RSP]);
+ c, ss_base(ctxt), c->regs[VCPU_REGS_RSP]);
break;
case 0x58 ... 0x5f: /* pop reg */
pop_instruction:
- if ((rc = ops->read_std(register_address(c, ctxt->ss_base,
+ if ((rc = ops->read_std(register_address(c, ss_base(ctxt),
c->regs[VCPU_REGS_RSP]), c->dst.ptr,
c->op_bytes, ctxt->vcpu)) != 0)
goto done;
@@ -1405,7 +1427,7 @@ special_insn:
c->rep_prefix ?
address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
(ctxt->eflags & EFLG_DF),
- register_address(c, ctxt->es_base,
+ register_address(c, es_base(ctxt),
c->regs[VCPU_REGS_RDI]),
c->rep_prefix,
c->regs[VCPU_REGS_RDX]) == 0) {
@@ -1421,9 +1443,8 @@ special_insn:
c->rep_prefix ?
address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
(ctxt->eflags & EFLG_DF),
- register_address(c, c->override_base ?
- *c->override_base :
- ctxt->ds_base,
+ register_address(c,
+ seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]),
c->rep_prefix,
c->regs[VCPU_REGS_RDX]) == 0) {
@@ -1559,11 +1580,10 @@ special_insn:
c->dst.type = OP_MEM;
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.ptr = (unsigned long *)register_address(c,
- ctxt->es_base,
+ es_base(ctxt),
c->regs[VCPU_REGS_RDI]);
if ((rc = ops->read_emulated(register_address(c,
- c->override_base ? *c->override_base :
- ctxt->ds_base,
+ seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]),
&c->dst.val,
c->dst.bytes, ctxt->vcpu)) != 0)
@@ -1579,8 +1599,7 @@ special_insn:
c->src.type = OP_NONE; /* Disable writeback. */
c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->src.ptr = (unsigned long *)register_address(c,
- c->override_base ? *c->override_base :
- ctxt->ds_base,
+ seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]);
if ((rc = ops->read_emulated((unsigned long)c->src.ptr,
&c->src.val,
@@ -1591,7 +1610,7 @@ special_insn:
c->dst.type = OP_NONE; /* Disable writeback. */
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.ptr = (unsigned long *)register_address(c,
- ctxt->es_base,
+ es_base(ctxt),
c->regs[VCPU_REGS_RDI]);
if ((rc = ops->read_emulated((unsigned long)c->dst.ptr,
&c->dst.val,
@@ -1615,7 +1634,7 @@ special_insn:
c->dst.type = OP_MEM;
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.ptr = (unsigned long *)register_address(c,
- ctxt->es_base,
+ es_base(ctxt),
c->regs[VCPU_REGS_RDI]);
c->dst.val = c->regs[VCPU_REGS_RAX];
register_address_increment(c, &c->regs[VCPU_REGS_RDI],
@@ -1627,8 +1646,7 @@ special_insn:
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
if ((rc = ops->read_emulated(register_address(c,
- c->override_base ? *c->override_base :
- ctxt->ds_base,
+ seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]),
&c->dst.val,
c->dst.bytes,
diff --git a/include/asm-x86/kvm_x86_emulate.h b/include/asm-x86/kvm_x86_emulate.h
index 9fda4b3..4e8c1e4 100644
--- a/include/asm-x86/kvm_x86_emulate.h
+++ b/include/asm-x86/kvm_x86_emulate.h
@@ -124,7 +124,8 @@ struct decode_cache {
u8 rex_prefix;
struct operand src;
struct operand dst;
- unsigned long *override_base;
+ bool has_seg_override;
+ u8 seg_override;
unsigned int d;
unsigned long regs[NR_VCPU_REGS];
unsigned long eip;
@@ -151,12 +152,7 @@ struct x86_emulate_ctxt {
/* Emulated execution mode, represented by an X86EMUL_MODE value. */
int mode;
- unsigned long cs_base;
- unsigned long ds_base;
- unsigned long es_base;
- unsigned long ss_base;
- unsigned long gs_base;
- unsigned long fs_base;
+ u32 cs_base;
/* decode cache */
--
1.5.6
next prev parent reply other threads:[~2008-06-26 12:35 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-26 12:27 [PATCH 00/50] KVM patches review for the 2.6.27 merge window Avi Kivity
2008-06-26 12:27 ` [PATCH 01/50] KVM: remove long -> void *user -> long cast Avi Kivity
2008-06-26 12:27 ` [PATCH 02/50] KVM: add statics were possible, function definition in lapic.h Avi Kivity
2008-06-26 12:27 ` [PATCH 03/50] KVM: VMX: move APIC_ACCESS trace entry to generic code Avi Kivity
2008-06-26 12:27 ` [PATCH 04/50] KVM: SVM: implement dedicated NMI exit handler Avi Kivity
2008-06-26 12:27 ` [PATCH 05/50] KVM: SVM: implement dedicated INTR " Avi Kivity
2008-06-26 12:27 ` [PATCH 06/50] KVM: add missing kvmtrace bits Avi Kivity
2008-06-26 12:27 ` [PATCH 07/50] KVM: SVM: add missing kvmtrace markers Avi Kivity
2008-06-26 12:27 ` [PATCH 08/50] KVM: SVM: add tracing support for TDP page faults Avi Kivity
2008-06-26 12:27 ` [PATCH 09/50] KVM: Handle vma regions with no backing page Avi Kivity
2008-06-26 12:27 ` [PATCH 10/50] KVM: PIT: support mode 3 Avi Kivity
2008-06-26 12:27 ` [PATCH 11/50] KVM: SVM: Fake MSR_K7 performance counters Avi Kivity
2008-06-26 12:27 ` [PATCH 12/50] KVM: VMX: Trivial vmcs_write64() code simplification Avi Kivity
2008-06-26 12:27 ` [PATCH 13/50] KVM: MMU: Fix false flooding when a pte points to page table Avi Kivity
2008-06-26 12:27 ` [PATCH 14/50] KVM: Handle virtualization instruction #UD faults during reboot Avi Kivity
2008-06-26 12:27 ` [PATCH 15/50] KVM: VMX: Add list of potentially locally cached vcpus Avi Kivity
2008-06-26 12:27 ` [PATCH 16/50] KVM: Remove decache_vcpus_on_cpu() and related callbacks Avi Kivity
2008-06-26 12:27 ` [PATCH 17/50] KVM: Remove unnecessary ->decache_regs() call Avi Kivity
2008-06-26 12:28 ` [PATCH 18/50] KVM: IOAPIC/LAPIC: Enable NMI support Avi Kivity
2008-06-26 12:28 ` [PATCH 19/50] KVM: VMX: Enable NMI with in-kernel irqchip Avi Kivity
2008-06-26 12:28 ` [PATCH 20/50] KVM: Order segment register constants in the same way as cpu operand encoding Avi Kivity
2008-06-26 12:28 ` [PATCH 21/50] KVM: MTRR support Avi Kivity
2008-06-26 12:28 ` [PATCH 22/50] KVM: Prefixes segment functions that will be exported with "kvm_" Avi Kivity
2008-06-26 12:28 ` [PATCH 23/50] KVM: x86 emulator: Update c->dst.bytes in decode instruction Avi Kivity
2008-06-26 12:28 ` [PATCH 24/50] KVM: x86 emulator: add support for jmp far 0xea Avi Kivity
2008-06-26 12:28 ` [PATCH 25/50] KVM: x86 emulator: adds support to mov r,imm (opcode 0xb8) instruction Avi Kivity
2008-06-26 12:28 ` [PATCH 26/50] KVM: x86 emulator: Add support for mov seg, r (0x8e) instruction Avi Kivity
2008-06-26 12:28 ` [PATCH 27/50] KVM: x86 emulator: Add support for mov r, sreg (0x8c) instruction Avi Kivity
2008-06-26 12:28 ` [PATCH 28/50] KVM: MMU: Optimize prefetch_page() Avi Kivity
2008-06-26 12:28 ` [PATCH 29/50] KVM: x86 emulator: simplify push imm8 emulation Avi Kivity
2008-06-26 12:28 ` [PATCH 30/50] KVM: x86 emulator: implement 'push imm' (opcode 0x68) Avi Kivity
2008-06-26 12:28 ` [PATCH 31/50] KVM: MMU: Move nonpaging_prefetch_page() Avi Kivity
2008-06-26 12:28 ` [PATCH 32/50] KVM: MMU: Avoid page prefetch on SVM Avi Kivity
2008-06-26 12:28 ` [PATCH 33/50] KVM: kvm_io_device: extend in_range() to manage len and write attribute Avi Kivity
2008-06-26 12:28 ` [PATCH 34/50] KVM: Add coalesced MMIO support (common part) Avi Kivity
2008-06-26 12:28 ` [PATCH 35/50] KVM: Add coalesced MMIO support (x86 part) Avi Kivity
2008-06-26 12:28 ` [PATCH 36/50] KVM: Add coalesced MMIO support (powerpc part) Avi Kivity
2008-06-26 12:28 ` [PATCH 37/50] KVM: Add coalesced MMIO support (ia64 part) Avi Kivity
2008-06-26 12:28 ` [PATCH 38/50] KVM: only abort guest entry if timer count goes from 0->1 Avi Kivity
2008-06-26 12:28 ` [PATCH 39/50] KVM: Do not calculate linear rip in emulation failure report Avi Kivity
2008-06-26 12:28 ` [PATCH 40/50] KVM: Support mixed endian machines Avi Kivity
2008-06-26 12:28 ` [PATCH 41/50] KVM: Use printk_rlimit() instead of reporting emulation failures just once Avi Kivity
2008-06-26 12:28 ` [PATCH 42/50] KVM: x86 emulator: emulate nop and xchg reg, acc (opcodes 0x90 - 0x97) Avi Kivity
2008-06-26 12:28 ` [PATCH 43/50] KVM: x86 emulator: handle undecoded rex.b with r/m = 5 in certain cases Avi Kivity
2008-06-26 12:28 ` [PATCH 44/50] KVM: x86 emulator: simplify sib decoding Avi Kivity
2008-06-26 12:28 ` [PATCH 45/50] KVM: x86 emulator: simplify r/m decoding Avi Kivity
2008-06-26 12:28 ` [PATCH 46/50] KVM: x86 emulator: simplify rip relative decoding Avi Kivity
2008-06-26 12:28 ` [PATCH 47/50] KVM: x86 emulator: avoid segment base adjust for lea Avi Kivity
2008-06-26 12:28 ` Avi Kivity [this message]
2008-06-26 12:28 ` [PATCH 49/50] KVM: MMU: When debug is enabled, make it a run-time parameter Avi Kivity
2008-06-26 12:28 ` [PATCH 50/50] KVM: MMU: Fix printk format Avi Kivity
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