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Date: Fri, 7 Jun 2013 16:03:19 -0700
From: David Daney <ddaney.cavm@...il.com>
To: linux-mips@...ux-mips.org, ralf@...ux-mips.org,
kvm@...r.kernel.org, Sanjay Lal <sanjayl@...asys.com>
Cc: linux-kernel@...r.kernel.org, David Daney <david.daney@...ium.com>
Subject: [PATCH 15/31] mips/kvm: Exception handling to leave and reenter guest mode.
From: David Daney <david.daney@...ium.com>
Currently this is a little complex, here are the facts about how it works:
o When running in Guest mode we set the high bit of CP0_XCONTEXT. If
this bit is clear, we don't do anything special on an exception.
o If we are in guest mode, upon an exception we:
1) load the stack pointer from the mips_kvm_rootsp array instead of
kernelsp.
2) Clear GuestCtl[GM] and high bit of CP0_XCONTEXT.
3) Restore host ASID and PGD pointer.
o Upon restarting from an exception we test the task TIF_GUESTMODE
flag if it is clear, nothing special is done.
o If Guest mode is active for the thread we:
1) Compare the stack pointer to mips_kvm_rootsp, if it doesn't match
we are not reentering guest mode, so no more special processing
is done.
2) If reentering guest mode:
2a) Set high bit of CP0_XCONTEXT and GuestCtl[GM].
2b) Set Guest mode ASID and PGD pointer.
This allows a single set of exception handlers to be used for both
host and guest mode operation.
Signed-off-by: David Daney <david.daney@...ium.com>
---
arch/mips/include/asm/stackframe.h | 135 ++++++++++++++++++++++++++++++++++++-
1 file changed, 132 insertions(+), 3 deletions(-)
diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
index 20627b2..bf2ec48 100644
--- a/arch/mips/include/asm/stackframe.h
+++ b/arch/mips/include/asm/stackframe.h
@@ -17,6 +17,7 @@
#include <asm/asmmacro.h>
#include <asm/mipsregs.h>
#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
/*
* For SMTC kernel, global IE should be left set, and interrupts
@@ -98,7 +99,9 @@
#define CPU_ID_REG CP0_CONTEXT
#define CPU_ID_MFC0 MFC0
#endif
- .macro get_saved_sp /* SMP variation */
+#define CPU_ID_MASK ((1 << 13) - 1)
+
+ .macro get_saved_sp_for_save_some /* SMP variation */
CPU_ID_MFC0 k0, CPU_ID_REG
#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
lui k1, %hi(kernelsp)
@@ -110,15 +113,49 @@
dsll k1, 16
#endif
LONG_SRL k0, PTEBASE_SHIFT
+#ifdef CONFIG_KVM_MIPSVZ
+ andi k0, CPU_ID_MASK /* high bits indicate guest mode. */
+#endif
LONG_ADDU k1, k0
LONG_L k1, %lo(kernelsp)(k1)
.endm
+ .macro get_saved_sp
+ CPU_ID_MFC0 k0, CPU_ID_REG
+ get_saved_sp_for_save_some
+ .endm
+
+ .macro get_mips_kvm_rootsp /* SMP variation */
+#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
+ lui k1, %hi(mips_kvm_rootsp)
+#else
+ lui k1, %highest(mips_kvm_rootsp)
+ daddiu k1, %higher(mips_kvm_rootsp)
+ dsll k1, 16
+ daddiu k1, %hi(mips_kvm_rootsp)
+ dsll k1, 16
+#endif
+ LONG_SRL k0, PTEBASE_SHIFT
+ andi k0, CPU_ID_MASK /* high bits indicate guest mode. */
+ LONG_ADDU k1, k0
+ LONG_L k1, %lo(mips_kvm_rootsp)(k1)
+ .endm
+
.macro set_saved_sp stackp temp temp2
CPU_ID_MFC0 \temp, CPU_ID_REG
LONG_SRL \temp, PTEBASE_SHIFT
+#ifdef CONFIG_KVM_MIPSVZ
+ andi k0, CPU_ID_MASK /* high bits indicate guest mode. */
+#endif
LONG_S \stackp, kernelsp(\temp)
.endm
+
+ .macro set_mips_kvm_rootsp stackp temp
+ CPU_ID_MFC0 \temp, CPU_ID_REG
+ LONG_SRL \temp, PTEBASE_SHIFT
+ andi k0, CPU_ID_MASK /* high bits indicate guest mode. */
+ LONG_S \stackp, mips_kvm_rootsp(\temp)
+ .endm
#else
.macro get_saved_sp /* Uniprocessor variation */
#ifdef CONFIG_CPU_JUMP_WORKAROUNDS
@@ -152,9 +189,27 @@
LONG_L k1, %lo(kernelsp)(k1)
.endm
+ .macro get_mips_kvm_rootsp /* Uniprocessor variation */
+#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
+ lui k1, %hi(mips_kvm_rootsp)
+#else
+ lui k1, %highest(mips_kvm_rootsp)
+ daddiu k1, %higher(mips_kvm_rootsp)
+ dsll k1, k1, 16
+ daddiu k1, %hi(mips_kvm_rootsp)
+ dsll k1, k1, 16
+#endif
+ LONG_L k1, %lo(mips_kvm_rootsp)(k1)
+ .endm
+
+
.macro set_saved_sp stackp temp temp2
LONG_S \stackp, kernelsp
.endm
+
+ .macro set_mips_kvm_rootsp stackp temp
+ LONG_S \stackp, mips_kvm_rootsp
+ .endm
#endif
.macro SAVE_SOME
@@ -164,11 +219,21 @@
mfc0 k0, CP0_STATUS
sll k0, 3 /* extract cu0 bit */
.set noreorder
+#ifdef CONFIG_KVM_MIPSVZ
+ bgez k0, 7f
+ CPU_ID_MFC0 k0, CPU_ID_REG
+ bgez k0, 8f
+ move k1, sp
+ get_mips_kvm_rootsp
+ b 8f
+ nop
+#else
bltz k0, 8f
move k1, sp
+#endif
.set reorder
/* Called from user mode, new stack. */
- get_saved_sp
+7: get_saved_sp_for_save_some
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
8: move k0, sp
PTR_SUBU sp, k1, PT_SIZE
@@ -227,6 +292,35 @@
LONG_S $31, PT_R31(sp)
ori $28, sp, _THREAD_MASK
xori $28, _THREAD_MASK
+#ifdef CONFIG_KVM_MIPSVZ
+ CPU_ID_MFC0 k0, CPU_ID_REG
+ .set noreorder
+ bgez k0, 8f
+ /* Must clear GuestCtl0[GM] */
+ dins k0, zero, 63, 1
+ .set reorder
+ dmtc0 k0, CPU_ID_REG
+ mfc0 k0, CP0_GUESTCTL0
+ ins k0, zero, MIPS_GUESTCTL0B_GM, 1
+ mtc0 k0, CP0_GUESTCTL0
+ LONG_L v0, TI_TASK($28)
+ lw v1, THREAD_MM_ASID(v0)
+ dmtc0 v1, CP0_ENTRYHI
+ LONG_L v1, TASK_MM(v0)
+ .set noreorder
+ jal tlbmiss_handler_setup_pgd_array
+ LONG_L a0, MM_PGD(v1)
+ .set reorder
+ /*
+ * With KVM_MIPSVZ, we must not clobber k0/k1
+ * they were saved before they were used
+ */
+8:
+ MFC0 k0, CP0_KSCRATCH1
+ MFC0 v1, CP0_KSCRATCH2
+ LONG_S k0, PT_R26(sp)
+ LONG_S v1, PT_R27(sp)
+#endif
#ifdef CONFIG_CPU_CAVIUM_OCTEON
.set mips64
pref 0, 0($28) /* Prefetch the current pointer */
@@ -439,10 +533,45 @@
.set mips0
#endif /* CONFIG_MIPS_MT_SMTC */
LONG_L v1, PT_EPC(sp)
+ LONG_L $25, PT_R25(sp)
MTC0 v1, CP0_EPC
+#ifdef CONFIG_KVM_MIPSVZ
+ /*
+ * Only if TIF_GUESTMODE && sp is the saved KVM sp, return to
+ * guest mode.
+ */
+ LONG_L v0, TI_FLAGS($28)
+ li k1, _TIF_GUESTMODE
+ and v0, v0, k1
+ beqz v0, 8f
+ CPU_ID_MFC0 k0, CPU_ID_REG
+ get_mips_kvm_rootsp
+ PTR_SUBU k1, k1, PT_SIZE
+ bne k1, sp, 8f
+ /* Set the high order bit of CPU_ID_REG to indicate guest mode. */
+ dli v0, 1
+ dmfc0 v1, CPU_ID_REG
+ dins v1, v0, 63, 1
+ dmtc0 v1, CPU_ID_REG
+ /* Must set GuestCtl0[GM] */
+ mfc0 v1, CP0_GUESTCTL0
+ ins v1, v0, MIPS_GUESTCTL0B_GM, 1
+ mtc0 v1, CP0_GUESTCTL0
+
+ LONG_L v0, TI_TASK($28)
+ lw v1, THREAD_GUEST_ASID(v0)
+ dmtc0 v1, CP0_ENTRYHI
+ LONG_L v1, THREAD_VCPU(v0)
+ LONG_L v1, KVM_VCPU_KVM(v1)
+ LONG_L v1, KVM_ARCH_IMPL(v1)
+ .set noreorder
+ jal tlbmiss_handler_setup_pgd_array
+ LONG_L a0, KVM_MIPS_VZ_PGD(v1)
+ .set reorder
+8:
+#endif
LONG_L $31, PT_R31(sp)
LONG_L $28, PT_R28(sp)
- LONG_L $25, PT_R25(sp)
#ifdef CONFIG_64BIT
LONG_L $8, PT_R8(sp)
LONG_L $9, PT_R9(sp)
--
1.7.11.7
--
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