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linux/arch/arm64/include/asm/kvm_arm.h
Catalin Marinas 0648505324 kvm: arm64: Enable hardware updates of the Access Flag for Stage 2 page tables 
The ARMv8.1 architecture extensions introduce support for hardware
updates of the access and dirty information in page table entries. With
VTCR_EL2.HA enabled (bit 21), when the CPU accesses an IPA with the
PTE_AF bit cleared in the stage 2 page table, instead of raising an
Access Flag fault to EL2 the CPU sets the actual page table entry bit
(10). To ensure that kernel modifications to the page table do not
inadvertently revert a bit set by hardware updates, certain Stage 2
software pte/pmd operations must be performed atomically.

The main user of the AF bit is the kvm_age_hva() mechanism. The
kvm_age_hva_handler() function performs a "test and clear young" action
on the pte/pmd. This needs to be atomic in respect of automatic hardware
updates of the AF bit. Since the AF bit is in the same position for both
Stage 1 and Stage 2, the patch reuses the existing
ptep_test_and_clear_young() functionality if
__HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG is defined. Otherwise, the
existing pte_young/pte_mkold mechanism is preserved.

The kvm_set_s2pte_readonly() (and the corresponding pmd equivalent) have
to perform atomic modifications in order to avoid a race with updates of
the AF bit. The arm64 implementation has been re-written using
exclusives.

Currently, kvm_set_s2pte_writable() (and pmd equivalent) take a pointer
argument and modify the pte/pmd in place. However, these functions are
only used on local variables rather than actual page table entries, so
it makes more sense to follow the pte_mkwrite() approach for stage 1
attributes. The change to kvm_s2pte_mkwrite() makes it clear that these
functions do not modify the actual page table entries.

The (pte|pmd)_mkyoung() uses on Stage 2 entries (setting the AF bit
explicitly) do not need to be modified since hardware updates of the
dirty status are not supported by KVM, so there is no possibility of
losing such information.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
2016-05-09 22:23:08 +02:00

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/*
* Copyright (C) 2012,2013 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ARM64_KVM_ARM_H__
#define __ARM64_KVM_ARM_H__
#include <asm/esr.h>
#include <asm/memory.h>
#include <asm/types.h>
/* Hyp Configuration Register (HCR) bits */
#define HCR_E2H (UL(1) << 34)
#define HCR_ID (UL(1) << 33)
#define HCR_CD (UL(1) << 32)
#define HCR_RW_SHIFT 31
#define HCR_RW (UL(1) << HCR_RW_SHIFT)
#define HCR_TRVM (UL(1) << 30)
#define HCR_HCD (UL(1) << 29)
#define HCR_TDZ (UL(1) << 28)
#define HCR_TGE (UL(1) << 27)
#define HCR_TVM (UL(1) << 26)
#define HCR_TTLB (UL(1) << 25)
#define HCR_TPU (UL(1) << 24)
#define HCR_TPC (UL(1) << 23)
#define HCR_TSW (UL(1) << 22)
#define HCR_TAC (UL(1) << 21)
#define HCR_TIDCP (UL(1) << 20)
#define HCR_TSC (UL(1) << 19)
#define HCR_TID3 (UL(1) << 18)
#define HCR_TID2 (UL(1) << 17)
#define HCR_TID1 (UL(1) << 16)
#define HCR_TID0 (UL(1) << 15)
#define HCR_TWE (UL(1) << 14)
#define HCR_TWI (UL(1) << 13)
#define HCR_DC (UL(1) << 12)
#define HCR_BSU (3 << 10)
#define HCR_BSU_IS (UL(1) << 10)
#define HCR_FB (UL(1) << 9)
#define HCR_VA (UL(1) << 8)
#define HCR_VI (UL(1) << 7)
#define HCR_VF (UL(1) << 6)
#define HCR_AMO (UL(1) << 5)
#define HCR_IMO (UL(1) << 4)
#define HCR_FMO (UL(1) << 3)
#define HCR_PTW (UL(1) << 2)
#define HCR_SWIO (UL(1) << 1)
#define HCR_VM (UL(1) << 0)
/*
* The bits we set in HCR:
* RW: 64bit by default, can be overridden for 32bit VMs
* TAC: Trap ACTLR
* TSC: Trap SMC
* TVM: Trap VM ops (until M+C set in SCTLR_EL1)
* TSW: Trap cache operations by set/way
* TWE: Trap WFE
* TWI: Trap WFI
* TIDCP: Trap L2CTLR/L2ECTLR
* BSU_IS: Upgrade barriers to the inner shareable domain
* FB: Force broadcast of all maintainance operations
* AMO: Override CPSR.A and enable signaling with VA
* IMO: Override CPSR.I and enable signaling with VI
* FMO: Override CPSR.F and enable signaling with VF
* SWIO: Turn set/way invalidates into set/way clean+invalidate
*/
#define HCR_GUEST_FLAGS (HCR_TSC | HCR_TSW | HCR_TWE | HCR_TWI | HCR_VM | \
HCR_TVM | HCR_BSU_IS | HCR_FB | HCR_TAC | \
HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW)
#define HCR_VIRT_EXCP_MASK (HCR_VA | HCR_VI | HCR_VF)
#define HCR_INT_OVERRIDE (HCR_FMO | HCR_IMO)
#define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)
/* Hyp System Control Register (SCTLR_EL2) bits */
#define SCTLR_EL2_EE (1 << 25)
#define SCTLR_EL2_WXN (1 << 19)
#define SCTLR_EL2_I (1 << 12)
#define SCTLR_EL2_SA (1 << 3)
#define SCTLR_EL2_C (1 << 2)
#define SCTLR_EL2_A (1 << 1)
#define SCTLR_EL2_M 1
#define SCTLR_EL2_FLAGS (SCTLR_EL2_M | SCTLR_EL2_A | SCTLR_EL2_C | \
SCTLR_EL2_SA | SCTLR_EL2_I)
/* TCR_EL2 Registers bits */
#define TCR_EL2_RES1 ((1 << 31) | (1 << 23))
#define TCR_EL2_TBI (1 << 20)
#define TCR_EL2_PS_SHIFT 16
#define TCR_EL2_PS_MASK (7 << TCR_EL2_PS_SHIFT)
#define TCR_EL2_PS_40B (2 << TCR_EL2_PS_SHIFT)
#define TCR_EL2_TG0_MASK TCR_TG0_MASK
#define TCR_EL2_SH0_MASK TCR_SH0_MASK
#define TCR_EL2_ORGN0_MASK TCR_ORGN0_MASK
#define TCR_EL2_IRGN0_MASK TCR_IRGN0_MASK
#define TCR_EL2_T0SZ_MASK 0x3f
#define TCR_EL2_MASK (TCR_EL2_TG0_MASK | TCR_EL2_SH0_MASK | \
TCR_EL2_ORGN0_MASK | TCR_EL2_IRGN0_MASK | TCR_EL2_T0SZ_MASK)
/* VTCR_EL2 Registers bits */
#define VTCR_EL2_RES1 (1 << 31)
#define VTCR_EL2_HD (1 << 22)
#define VTCR_EL2_HA (1 << 21)
#define VTCR_EL2_PS_MASK TCR_EL2_PS_MASK
#define VTCR_EL2_TG0_MASK TCR_TG0_MASK
#define VTCR_EL2_TG0_4K TCR_TG0_4K
#define VTCR_EL2_TG0_16K TCR_TG0_16K
#define VTCR_EL2_TG0_64K TCR_TG0_64K
#define VTCR_EL2_SH0_MASK TCR_SH0_MASK
#define VTCR_EL2_SH0_INNER TCR_SH0_INNER
#define VTCR_EL2_ORGN0_MASK TCR_ORGN0_MASK
#define VTCR_EL2_ORGN0_WBWA TCR_ORGN0_WBWA
#define VTCR_EL2_IRGN0_MASK TCR_IRGN0_MASK
#define VTCR_EL2_IRGN0_WBWA TCR_IRGN0_WBWA
#define VTCR_EL2_SL0_SHIFT 6
#define VTCR_EL2_SL0_MASK (3 << VTCR_EL2_SL0_SHIFT)
#define VTCR_EL2_SL0_LVL1 (1 << VTCR_EL2_SL0_SHIFT)
#define VTCR_EL2_T0SZ_MASK 0x3f
#define VTCR_EL2_T0SZ_40B 24
#define VTCR_EL2_VS_SHIFT 19
#define VTCR_EL2_VS_8BIT (0 << VTCR_EL2_VS_SHIFT)
#define VTCR_EL2_VS_16BIT (1 << VTCR_EL2_VS_SHIFT)
/*
* We configure the Stage-2 page tables to always restrict the IPA space to be
* 40 bits wide (T0SZ = 24). Systems with a PARange smaller than 40 bits are
* not known to exist and will break with this configuration.
*
* VTCR_EL2.PS is extracted from ID_AA64MMFR0_EL1.PARange at boot time
* (see hyp-init.S).
*
* Note that when using 4K pages, we concatenate two first level page tables
* together. With 16K pages, we concatenate 16 first level page tables.
*
* The magic numbers used for VTTBR_X in this patch can be found in Tables
* D4-23 and D4-25 in ARM DDI 0487A.b.
*/
#define VTCR_EL2_T0SZ_IPA VTCR_EL2_T0SZ_40B
#define VTCR_EL2_COMMON_BITS (VTCR_EL2_SH0_INNER | VTCR_EL2_ORGN0_WBWA | \
VTCR_EL2_IRGN0_WBWA | VTCR_EL2_RES1)
#ifdef CONFIG_ARM64_64K_PAGES
/*
* Stage2 translation configuration:
* 64kB pages (TG0 = 1)
* 2 level page tables (SL = 1)
*/
#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_64K | VTCR_EL2_SL0_LVL1)
#define VTTBR_X_TGRAN_MAGIC 38
#elif defined(CONFIG_ARM64_16K_PAGES)
/*
* Stage2 translation configuration:
* 16kB pages (TG0 = 2)
* 2 level page tables (SL = 1)
*/
#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_16K | VTCR_EL2_SL0_LVL1)
#define VTTBR_X_TGRAN_MAGIC 42
#else /* 4K */
/*
* Stage2 translation configuration:
* 4kB pages (TG0 = 0)
* 3 level page tables (SL = 1)
*/
#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_4K | VTCR_EL2_SL0_LVL1)
#define VTTBR_X_TGRAN_MAGIC 37
#endif
#define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN_FLAGS)
#define VTTBR_X (VTTBR_X_TGRAN_MAGIC - VTCR_EL2_T0SZ_IPA)
#define VTTBR_BADDR_SHIFT (VTTBR_X - 1)
#define VTTBR_BADDR_MASK (((UL(1) << (PHYS_MASK_SHIFT - VTTBR_X)) - 1) << VTTBR_BADDR_SHIFT)
#define VTTBR_VMID_SHIFT (UL(48))
#define VTTBR_VMID_MASK(size) (_AT(u64, (1 << size) - 1) << VTTBR_VMID_SHIFT)
/* Hyp System Trap Register */
#define HSTR_EL2_T(x) (1 << x)
/* Hyp Coproccessor Trap Register Shifts */
#define CPTR_EL2_TFP_SHIFT 10
/* Hyp Coprocessor Trap Register */
#define CPTR_EL2_TCPAC (1 << 31)
#define CPTR_EL2_TTA (1 << 20)
#define CPTR_EL2_TFP (1 << CPTR_EL2_TFP_SHIFT)
#define CPTR_EL2_DEFAULT 0x000033ff
/* Hyp Debug Configuration Register bits */
#define MDCR_EL2_TDRA (1 << 11)
#define MDCR_EL2_TDOSA (1 << 10)
#define MDCR_EL2_TDA (1 << 9)
#define MDCR_EL2_TDE (1 << 8)
#define MDCR_EL2_HPME (1 << 7)
#define MDCR_EL2_TPM (1 << 6)
#define MDCR_EL2_TPMCR (1 << 5)
#define MDCR_EL2_HPMN_MASK (0x1F)
/* For compatibility with fault code shared with 32-bit */
#define FSC_FAULT ESR_ELx_FSC_FAULT
#define FSC_ACCESS ESR_ELx_FSC_ACCESS
#define FSC_PERM ESR_ELx_FSC_PERM
/* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
#define HPFAR_MASK (~UL(0xf))
#define kvm_arm_exception_type \
{0, "IRQ" }, \
{1, "TRAP" }
#define ECN(x) { ESR_ELx_EC_##x, #x }
#define kvm_arm_exception_class \
ECN(UNKNOWN), ECN(WFx), ECN(CP15_32), ECN(CP15_64), ECN(CP14_MR), \
ECN(CP14_LS), ECN(FP_ASIMD), ECN(CP10_ID), ECN(CP14_64), ECN(SVC64), \
ECN(HVC64), ECN(SMC64), ECN(SYS64), ECN(IMP_DEF), ECN(IABT_LOW), \
ECN(IABT_CUR), ECN(PC_ALIGN), ECN(DABT_LOW), ECN(DABT_CUR), \
ECN(SP_ALIGN), ECN(FP_EXC32), ECN(FP_EXC64), ECN(SERROR), \
ECN(BREAKPT_LOW), ECN(BREAKPT_CUR), ECN(SOFTSTP_LOW), \
ECN(SOFTSTP_CUR), ECN(WATCHPT_LOW), ECN(WATCHPT_CUR), \
ECN(BKPT32), ECN(VECTOR32), ECN(BRK64)
#define CPACR_EL1_FPEN (3 << 20)
#define CPACR_EL1_TTA (1 << 28)
#endif /* __ARM64_KVM_ARM_H__ */
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