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alistair23-linux/arch/powerpc/kvm/book3s_pr_papr.c
David Gibson 99342cf804 kvmppc: Implement H_LOGICAL_CI_{LOAD,STORE} in KVM 
On POWER, storage caching is usually configured via the MMU - attributes
such as cache-inhibited are stored in the TLB and the hashed page table.

This makes correctly performing cache inhibited IO accesses awkward when
the MMU is turned off (real mode).  Some CPU models provide special
registers to control the cache attributes of real mode load and stores but
this is not at all consistent.  This is a problem in particular for SLOF,
the firmware used on KVM guests, which runs entirely in real mode, but
which needs to do IO to load the kernel.

To simplify this qemu implements two special hypercalls, H_LOGICAL_CI_LOAD
and H_LOGICAL_CI_STORE which simulate a cache-inhibited load or store to
a logical address (aka guest physical address).  SLOF uses these for IO.

However, because these are implemented within qemu, not the host kernel,
these bypass any IO devices emulated within KVM itself.  The simplest way
to see this problem is to attempt to boot a KVM guest from a virtio-blk
device with iothread / dataplane enabled.  The iothread code relies on an
in kernel implementation of the virtio queue notification, which is not
triggered by the IO hcalls, and so the guest will stall in SLOF unable to
load the guest OS.

This patch addresses this by providing in-kernel implementations of the
2 hypercalls, which correctly scan the KVM IO bus.  Any access to an
address not handled by the KVM IO bus will cause a VM exit, hitting the
qemu implementation as before.

Note that a userspace change is also required, in order to enable these
new hcall implementations with KVM_CAP_PPC_ENABLE_HCALL.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
[agraf: fix compilation]
Signed-off-by: Alexander Graf <agraf@suse.de>
2015-04-21 15:21:28 +02:00

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/*
* Copyright (C) 2011. Freescale Inc. All rights reserved.
*
* Authors:
* Alexander Graf <agraf@suse.de>
* Paul Mackerras <paulus@samba.org>
*
* Description:
*
* Hypercall handling for running PAPR guests in PR KVM on Book 3S
* processors.
*
* 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.
*/
#include <linux/anon_inodes.h>
#include <asm/uaccess.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#define HPTE_SIZE 16 /* bytes per HPT entry */
static unsigned long get_pteg_addr(struct kvm_vcpu *vcpu, long pte_index)
{
struct kvmppc_vcpu_book3s *vcpu_book3s = to_book3s(vcpu);
unsigned long pteg_addr;
pte_index <<= 4;
pte_index &= ((1 << ((vcpu_book3s->sdr1 & 0x1f) + 11)) - 1) << 7 | 0x70;
pteg_addr = vcpu_book3s->sdr1 & 0xfffffffffffc0000ULL;
pteg_addr |= pte_index;
return pteg_addr;
}
static int kvmppc_h_pr_enter(struct kvm_vcpu *vcpu)
{
long flags = kvmppc_get_gpr(vcpu, 4);
long pte_index = kvmppc_get_gpr(vcpu, 5);
__be64 pteg[2 * 8];
__be64 *hpte;
unsigned long pteg_addr, i;
long int ret;
i = pte_index & 7;
pte_index &= ~7UL;
pteg_addr = get_pteg_addr(vcpu, pte_index);
mutex_lock(&vcpu->kvm->arch.hpt_mutex);
copy_from_user(pteg, (void __user *)pteg_addr, sizeof(pteg));
hpte = pteg;
ret = H_PTEG_FULL;
if (likely((flags & H_EXACT) == 0)) {
for (i = 0; ; ++i) {
if (i == 8)
goto done;
if ((be64_to_cpu(*hpte) & HPTE_V_VALID) == 0)
break;
hpte += 2;
}
} else {
hpte += i * 2;
if (*hpte & HPTE_V_VALID)
goto done;
}
hpte[0] = cpu_to_be64(kvmppc_get_gpr(vcpu, 6));
hpte[1] = cpu_to_be64(kvmppc_get_gpr(vcpu, 7));
pteg_addr += i * HPTE_SIZE;
copy_to_user((void __user *)pteg_addr, hpte, HPTE_SIZE);
kvmppc_set_gpr(vcpu, 4, pte_index | i);
ret = H_SUCCESS;
done:
mutex_unlock(&vcpu->kvm->arch.hpt_mutex);
kvmppc_set_gpr(vcpu, 3, ret);
return EMULATE_DONE;
}
static int kvmppc_h_pr_remove(struct kvm_vcpu *vcpu)
{
unsigned long flags= kvmppc_get_gpr(vcpu, 4);
unsigned long pte_index = kvmppc_get_gpr(vcpu, 5);
unsigned long avpn = kvmppc_get_gpr(vcpu, 6);
unsigned long v = 0, pteg, rb;
unsigned long pte[2];
long int ret;
pteg = get_pteg_addr(vcpu, pte_index);
mutex_lock(&vcpu->kvm->arch.hpt_mutex);
copy_from_user(pte, (void __user *)pteg, sizeof(pte));
pte[0] = be64_to_cpu((__force __be64)pte[0]);
pte[1] = be64_to_cpu((__force __be64)pte[1]);
ret = H_NOT_FOUND;
if ((pte[0] & HPTE_V_VALID) == 0 ||
((flags & H_AVPN) && (pte[0] & ~0x7fUL) != avpn) ||
((flags & H_ANDCOND) && (pte[0] & avpn) != 0))
goto done;
copy_to_user((void __user *)pteg, &v, sizeof(v));
rb = compute_tlbie_rb(pte[0], pte[1], pte_index);
vcpu->arch.mmu.tlbie(vcpu, rb, rb & 1 ? true : false);
ret = H_SUCCESS;
kvmppc_set_gpr(vcpu, 4, pte[0]);
kvmppc_set_gpr(vcpu, 5, pte[1]);
done:
mutex_unlock(&vcpu->kvm->arch.hpt_mutex);
kvmppc_set_gpr(vcpu, 3, ret);
return EMULATE_DONE;
}
/* Request defs for kvmppc_h_pr_bulk_remove() */
#define H_BULK_REMOVE_TYPE 0xc000000000000000ULL
#define H_BULK_REMOVE_REQUEST 0x4000000000000000ULL
#define H_BULK_REMOVE_RESPONSE 0x8000000000000000ULL
#define H_BULK_REMOVE_END 0xc000000000000000ULL
#define H_BULK_REMOVE_CODE 0x3000000000000000ULL
#define H_BULK_REMOVE_SUCCESS 0x0000000000000000ULL
#define H_BULK_REMOVE_NOT_FOUND 0x1000000000000000ULL
#define H_BULK_REMOVE_PARM 0x2000000000000000ULL
#define H_BULK_REMOVE_HW 0x3000000000000000ULL
#define H_BULK_REMOVE_RC 0x0c00000000000000ULL
#define H_BULK_REMOVE_FLAGS 0x0300000000000000ULL
#define H_BULK_REMOVE_ABSOLUTE 0x0000000000000000ULL
#define H_BULK_REMOVE_ANDCOND 0x0100000000000000ULL
#define H_BULK_REMOVE_AVPN 0x0200000000000000ULL
#define H_BULK_REMOVE_PTEX 0x00ffffffffffffffULL
#define H_BULK_REMOVE_MAX_BATCH 4
static int kvmppc_h_pr_bulk_remove(struct kvm_vcpu *vcpu)
{
int i;
int paramnr = 4;
int ret = H_SUCCESS;
mutex_lock(&vcpu->kvm->arch.hpt_mutex);
for (i = 0; i < H_BULK_REMOVE_MAX_BATCH; i++) {
unsigned long tsh = kvmppc_get_gpr(vcpu, paramnr+(2*i));
unsigned long tsl = kvmppc_get_gpr(vcpu, paramnr+(2*i)+1);
unsigned long pteg, rb, flags;
unsigned long pte[2];
unsigned long v = 0;
if ((tsh & H_BULK_REMOVE_TYPE) == H_BULK_REMOVE_END) {
break; /* Exit success */
} else if ((tsh & H_BULK_REMOVE_TYPE) !=
H_BULK_REMOVE_REQUEST) {
ret = H_PARAMETER;
break; /* Exit fail */
}
tsh &= H_BULK_REMOVE_PTEX | H_BULK_REMOVE_FLAGS;
tsh |= H_BULK_REMOVE_RESPONSE;
if ((tsh & H_BULK_REMOVE_ANDCOND) &&
(tsh & H_BULK_REMOVE_AVPN)) {
tsh |= H_BULK_REMOVE_PARM;
kvmppc_set_gpr(vcpu, paramnr+(2*i), tsh);
ret = H_PARAMETER;
break; /* Exit fail */
}
pteg = get_pteg_addr(vcpu, tsh & H_BULK_REMOVE_PTEX);
copy_from_user(pte, (void __user *)pteg, sizeof(pte));
pte[0] = be64_to_cpu((__force __be64)pte[0]);
pte[1] = be64_to_cpu((__force __be64)pte[1]);
/* tsl = AVPN */
flags = (tsh & H_BULK_REMOVE_FLAGS) >> 26;
if ((pte[0] & HPTE_V_VALID) == 0 ||
((flags & H_AVPN) && (pte[0] & ~0x7fUL) != tsl) ||
((flags & H_ANDCOND) && (pte[0] & tsl) != 0)) {
tsh |= H_BULK_REMOVE_NOT_FOUND;
} else {
/* Splat the pteg in (userland) hpt */
copy_to_user((void __user *)pteg, &v, sizeof(v));
rb = compute_tlbie_rb(pte[0], pte[1],
tsh & H_BULK_REMOVE_PTEX);
vcpu->arch.mmu.tlbie(vcpu, rb, rb & 1 ? true : false);
tsh |= H_BULK_REMOVE_SUCCESS;
tsh |= (pte[1] & (HPTE_R_C | HPTE_R_R)) << 43;
}
kvmppc_set_gpr(vcpu, paramnr+(2*i), tsh);
}
mutex_unlock(&vcpu->kvm->arch.hpt_mutex);
kvmppc_set_gpr(vcpu, 3, ret);
return EMULATE_DONE;
}
static int kvmppc_h_pr_protect(struct kvm_vcpu *vcpu)
{
unsigned long flags = kvmppc_get_gpr(vcpu, 4);
unsigned long pte_index = kvmppc_get_gpr(vcpu, 5);
unsigned long avpn = kvmppc_get_gpr(vcpu, 6);
unsigned long rb, pteg, r, v;
unsigned long pte[2];
long int ret;
pteg = get_pteg_addr(vcpu, pte_index);
mutex_lock(&vcpu->kvm->arch.hpt_mutex);
copy_from_user(pte, (void __user *)pteg, sizeof(pte));
pte[0] = be64_to_cpu((__force __be64)pte[0]);
pte[1] = be64_to_cpu((__force __be64)pte[1]);
ret = H_NOT_FOUND;
if ((pte[0] & HPTE_V_VALID) == 0 ||
((flags & H_AVPN) && (pte[0] & ~0x7fUL) != avpn))
goto done;
v = pte[0];
r = pte[1];
r &= ~(HPTE_R_PP0 | HPTE_R_PP | HPTE_R_N | HPTE_R_KEY_HI |
HPTE_R_KEY_LO);
r |= (flags << 55) & HPTE_R_PP0;
r |= (flags << 48) & HPTE_R_KEY_HI;
r |= flags & (HPTE_R_PP | HPTE_R_N | HPTE_R_KEY_LO);
pte[1] = r;
rb = compute_tlbie_rb(v, r, pte_index);
vcpu->arch.mmu.tlbie(vcpu, rb, rb & 1 ? true : false);
pte[0] = (__force u64)cpu_to_be64(pte[0]);
pte[1] = (__force u64)cpu_to_be64(pte[1]);
copy_to_user((void __user *)pteg, pte, sizeof(pte));
ret = H_SUCCESS;
done:
mutex_unlock(&vcpu->kvm->arch.hpt_mutex);
kvmppc_set_gpr(vcpu, 3, ret);
return EMULATE_DONE;
}
static int kvmppc_h_pr_put_tce(struct kvm_vcpu *vcpu)
{
unsigned long liobn = kvmppc_get_gpr(vcpu, 4);
unsigned long ioba = kvmppc_get_gpr(vcpu, 5);
unsigned long tce = kvmppc_get_gpr(vcpu, 6);
long rc;
rc = kvmppc_h_put_tce(vcpu, liobn, ioba, tce);
if (rc == H_TOO_HARD)
return EMULATE_FAIL;
kvmppc_set_gpr(vcpu, 3, rc);
return EMULATE_DONE;
}
static int kvmppc_h_pr_logical_ci_load(struct kvm_vcpu *vcpu)
{
long rc;
rc = kvmppc_h_logical_ci_load(vcpu);
if (rc == H_TOO_HARD)
return EMULATE_FAIL;
kvmppc_set_gpr(vcpu, 3, rc);
return EMULATE_DONE;
}
static int kvmppc_h_pr_logical_ci_store(struct kvm_vcpu *vcpu)
{
long rc;
rc = kvmppc_h_logical_ci_store(vcpu);
if (rc == H_TOO_HARD)
return EMULATE_FAIL;
kvmppc_set_gpr(vcpu, 3, rc);
return EMULATE_DONE;
}
static int kvmppc_h_pr_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd)
{
long rc = kvmppc_xics_hcall(vcpu, cmd);
kvmppc_set_gpr(vcpu, 3, rc);
return EMULATE_DONE;
}
int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
{
int rc, idx;
if (cmd <= MAX_HCALL_OPCODE &&
!test_bit(cmd/4, vcpu->kvm->arch.enabled_hcalls))
return EMULATE_FAIL;
switch (cmd) {
case H_ENTER:
return kvmppc_h_pr_enter(vcpu);
case H_REMOVE:
return kvmppc_h_pr_remove(vcpu);
case H_PROTECT:
return kvmppc_h_pr_protect(vcpu);
case H_BULK_REMOVE:
return kvmppc_h_pr_bulk_remove(vcpu);
case H_PUT_TCE:
return kvmppc_h_pr_put_tce(vcpu);
case H_CEDE:
kvmppc_set_msr_fast(vcpu, kvmppc_get_msr(vcpu) | MSR_EE);
kvm_vcpu_block(vcpu);
clear_bit(KVM_REQ_UNHALT, &vcpu->requests);
vcpu->stat.halt_wakeup++;
return EMULATE_DONE;
case H_LOGICAL_CI_LOAD:
return kvmppc_h_pr_logical_ci_load(vcpu);
case H_LOGICAL_CI_STORE:
return kvmppc_h_pr_logical_ci_store(vcpu);
case H_XIRR:
case H_CPPR:
case H_EOI:
case H_IPI:
case H_IPOLL:
case H_XIRR_X:
if (kvmppc_xics_enabled(vcpu))
return kvmppc_h_pr_xics_hcall(vcpu, cmd);
break;
case H_RTAS:
if (list_empty(&vcpu->kvm->arch.rtas_tokens))
break;
idx = srcu_read_lock(&vcpu->kvm->srcu);
rc = kvmppc_rtas_hcall(vcpu);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
if (rc)
break;
kvmppc_set_gpr(vcpu, 3, 0);
return EMULATE_DONE;
}
return EMULATE_FAIL;
}
int kvmppc_hcall_impl_pr(unsigned long cmd)
{
switch (cmd) {
case H_ENTER:
case H_REMOVE:
case H_PROTECT:
case H_BULK_REMOVE:
case H_PUT_TCE:
case H_CEDE:
case H_LOGICAL_CI_LOAD:
case H_LOGICAL_CI_STORE:
#ifdef CONFIG_KVM_XICS
case H_XIRR:
case H_CPPR:
case H_EOI:
case H_IPI:
case H_IPOLL:
case H_XIRR_X:
#endif
return 1;
}
return 0;
}
/*
* List of hcall numbers to enable by default.
* For compatibility with old userspace, we enable by default
* all hcalls that were implemented before the hcall-enabling
* facility was added. Note this list should not include H_RTAS.
*/
static unsigned int default_hcall_list[] = {
H_ENTER,
H_REMOVE,
H_PROTECT,
H_BULK_REMOVE,
H_PUT_TCE,
H_CEDE,
#ifdef CONFIG_KVM_XICS
H_XIRR,
H_CPPR,
H_EOI,
H_IPI,
H_IPOLL,
H_XIRR_X,
#endif
0
};
void kvmppc_pr_init_default_hcalls(struct kvm *kvm)
{
int i;
unsigned int hcall;
for (i = 0; default_hcall_list[i]; ++i) {
hcall = default_hcall_list[i];
WARN_ON(!kvmppc_hcall_impl_pr(hcall));
__set_bit(hcall / 4, kvm->arch.enabled_hcalls);
}
}
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