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linux/arch/s390/kvm/priv.c
Christian Borntraeger 1eddb85f88 KVM: s390: Fix tprot locking 
There is a potential host deadlock in the tprot intercept handling.
We must not hold the mmap semaphore while resolving the guest
address. If userspace is remapping, then the memory detection in
the guest is broken anyway so we can safely separate the
address translation from walking the vmas.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2011-11-17 16:25:48 +02:00

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/*
* priv.c - handling privileged instructions
*
* Copyright IBM Corp. 2008
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (version 2 only)
* as published by the Free Software Foundation.
*
* Author(s): Carsten Otte <cotte@de.ibm.com>
* Christian Borntraeger <borntraeger@de.ibm.com>
*/
#include <linux/kvm.h>
#include <linux/gfp.h>
#include <linux/errno.h>
#include <asm/current.h>
#include <asm/debug.h>
#include <asm/ebcdic.h>
#include <asm/sysinfo.h>
#include "gaccess.h"
#include "kvm-s390.h"
static int handle_set_prefix(struct kvm_vcpu *vcpu)
{
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
u64 operand2;
u32 address = 0;
u8 tmp;
vcpu->stat.instruction_spx++;
operand2 = disp2;
if (base2)
operand2 += vcpu->arch.guest_gprs[base2];
/* must be word boundary */
if (operand2 & 3) {
kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
goto out;
}
/* get the value */
if (get_guest_u32(vcpu, operand2, &address)) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
goto out;
}
address = address & 0x7fffe000u;
/* make sure that the new value is valid memory */
if (copy_from_guest_absolute(vcpu, &tmp, address, 1) ||
(copy_from_guest_absolute(vcpu, &tmp, address + PAGE_SIZE, 1))) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
goto out;
}
vcpu->arch.sie_block->prefix = address;
vcpu->arch.sie_block->ihcpu = 0xffff;
VCPU_EVENT(vcpu, 5, "setting prefix to %x", address);
out:
return 0;
}
static int handle_store_prefix(struct kvm_vcpu *vcpu)
{
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
u64 operand2;
u32 address;
vcpu->stat.instruction_stpx++;
operand2 = disp2;
if (base2)
operand2 += vcpu->arch.guest_gprs[base2];
/* must be word boundary */
if (operand2 & 3) {
kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
goto out;
}
address = vcpu->arch.sie_block->prefix;
address = address & 0x7fffe000u;
/* get the value */
if (put_guest_u32(vcpu, operand2, address)) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
goto out;
}
VCPU_EVENT(vcpu, 5, "storing prefix to %x", address);
out:
return 0;
}
static int handle_store_cpu_address(struct kvm_vcpu *vcpu)
{
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
u64 useraddr;
int rc;
vcpu->stat.instruction_stap++;
useraddr = disp2;
if (base2)
useraddr += vcpu->arch.guest_gprs[base2];
if (useraddr & 1) {
kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
goto out;
}
rc = put_guest_u16(vcpu, useraddr, vcpu->vcpu_id);
if (rc == -EFAULT) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
goto out;
}
VCPU_EVENT(vcpu, 5, "storing cpu address to %llx", useraddr);
out:
return 0;
}
static int handle_skey(struct kvm_vcpu *vcpu)
{
vcpu->stat.instruction_storage_key++;
vcpu->arch.sie_block->gpsw.addr -= 4;
VCPU_EVENT(vcpu, 4, "%s", "retrying storage key operation");
return 0;
}
static int handle_stsch(struct kvm_vcpu *vcpu)
{
vcpu->stat.instruction_stsch++;
VCPU_EVENT(vcpu, 4, "%s", "store subchannel - CC3");
/* condition code 3 */
vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
vcpu->arch.sie_block->gpsw.mask |= (3 & 3ul) << 44;
return 0;
}
static int handle_chsc(struct kvm_vcpu *vcpu)
{
vcpu->stat.instruction_chsc++;
VCPU_EVENT(vcpu, 4, "%s", "channel subsystem call - CC3");
/* condition code 3 */
vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
vcpu->arch.sie_block->gpsw.mask |= (3 & 3ul) << 44;
return 0;
}
static int handle_stfl(struct kvm_vcpu *vcpu)
{
unsigned int facility_list;
int rc;
vcpu->stat.instruction_stfl++;
/* only pass the facility bits, which we can handle */
facility_list = S390_lowcore.stfl_fac_list & 0xff00fff3;
rc = copy_to_guest(vcpu, offsetof(struct _lowcore, stfl_fac_list),
&facility_list, sizeof(facility_list));
if (rc == -EFAULT)
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
else
VCPU_EVENT(vcpu, 5, "store facility list value %x",
facility_list);
return 0;
}
static int handle_stidp(struct kvm_vcpu *vcpu)
{
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
u64 operand2;
int rc;
vcpu->stat.instruction_stidp++;
operand2 = disp2;
if (base2)
operand2 += vcpu->arch.guest_gprs[base2];
if (operand2 & 7) {
kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
goto out;
}
rc = put_guest_u64(vcpu, operand2, vcpu->arch.stidp_data);
if (rc == -EFAULT) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
goto out;
}
VCPU_EVENT(vcpu, 5, "%s", "store cpu id");
out:
return 0;
}
static void handle_stsi_3_2_2(struct kvm_vcpu *vcpu, struct sysinfo_3_2_2 *mem)
{
struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
int cpus = 0;
int n;
spin_lock(&fi->lock);
for (n = 0; n < KVM_MAX_VCPUS; n++)
if (fi->local_int[n])
cpus++;
spin_unlock(&fi->lock);
/* deal with other level 3 hypervisors */
if (stsi(mem, 3, 2, 2) == -ENOSYS)
mem->count = 0;
if (mem->count < 8)
mem->count++;
for (n = mem->count - 1; n > 0 ; n--)
memcpy(&mem->vm[n], &mem->vm[n - 1], sizeof(mem->vm[0]));
mem->vm[0].cpus_total = cpus;
mem->vm[0].cpus_configured = cpus;
mem->vm[0].cpus_standby = 0;
mem->vm[0].cpus_reserved = 0;
mem->vm[0].caf = 1000;
memcpy(mem->vm[0].name, "KVMguest", 8);
ASCEBC(mem->vm[0].name, 8);
memcpy(mem->vm[0].cpi, "KVM/Linux ", 16);
ASCEBC(mem->vm[0].cpi, 16);
}
static int handle_stsi(struct kvm_vcpu *vcpu)
{
int fc = (vcpu->arch.guest_gprs[0] & 0xf0000000) >> 28;
int sel1 = vcpu->arch.guest_gprs[0] & 0xff;
int sel2 = vcpu->arch.guest_gprs[1] & 0xffff;
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
u64 operand2;
unsigned long mem;
vcpu->stat.instruction_stsi++;
VCPU_EVENT(vcpu, 4, "stsi: fc: %x sel1: %x sel2: %x", fc, sel1, sel2);
operand2 = disp2;
if (base2)
operand2 += vcpu->arch.guest_gprs[base2];
if (operand2 & 0xfff && fc > 0)
return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
switch (fc) {
case 0:
vcpu->arch.guest_gprs[0] = 3 << 28;
vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
return 0;
case 1: /* same handling for 1 and 2 */
case 2:
mem = get_zeroed_page(GFP_KERNEL);
if (!mem)
goto out_fail;
if (stsi((void *) mem, fc, sel1, sel2) == -ENOSYS)
goto out_mem;
break;
case 3:
if (sel1 != 2 || sel2 != 2)
goto out_fail;
mem = get_zeroed_page(GFP_KERNEL);
if (!mem)
goto out_fail;
handle_stsi_3_2_2(vcpu, (void *) mem);
break;
default:
goto out_fail;
}
if (copy_to_guest_absolute(vcpu, operand2, (void *) mem, PAGE_SIZE)) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
goto out_mem;
}
free_page(mem);
vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
vcpu->arch.guest_gprs[0] = 0;
return 0;
out_mem:
free_page(mem);
out_fail:
/* condition code 3 */
vcpu->arch.sie_block->gpsw.mask |= 3ul << 44;
return 0;
}
static intercept_handler_t priv_handlers[256] = {
[0x02] = handle_stidp,
[0x10] = handle_set_prefix,
[0x11] = handle_store_prefix,
[0x12] = handle_store_cpu_address,
[0x29] = handle_skey,
[0x2a] = handle_skey,
[0x2b] = handle_skey,
[0x34] = handle_stsch,
[0x5f] = handle_chsc,
[0x7d] = handle_stsi,
[0xb1] = handle_stfl,
};
int kvm_s390_handle_b2(struct kvm_vcpu *vcpu)
{
intercept_handler_t handler;
/*
* a lot of B2 instructions are priviledged. We first check for
* the privileged ones, that we can handle in the kernel. If the
* kernel can handle this instruction, we check for the problem
* state bit and (a) handle the instruction or (b) send a code 2
* program check.
* Anything else goes to userspace.*/
handler = priv_handlers[vcpu->arch.sie_block->ipa & 0x00ff];
if (handler) {
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
return kvm_s390_inject_program_int(vcpu,
PGM_PRIVILEGED_OPERATION);
else
return handler(vcpu);
}
return -EOPNOTSUPP;
}
static int handle_tprot(struct kvm_vcpu *vcpu)
{
int base1 = (vcpu->arch.sie_block->ipb & 0xf0000000) >> 28;
int disp1 = (vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16;
int base2 = (vcpu->arch.sie_block->ipb & 0xf000) >> 12;
int disp2 = vcpu->arch.sie_block->ipb & 0x0fff;
u64 address1 = disp1 + base1 ? vcpu->arch.guest_gprs[base1] : 0;
u64 address2 = disp2 + base2 ? vcpu->arch.guest_gprs[base2] : 0;
struct vm_area_struct *vma;
unsigned long user_address;
vcpu->stat.instruction_tprot++;
/* we only handle the Linux memory detection case:
* access key == 0
* guest DAT == off
* everything else goes to userspace. */
if (address2 & 0xf0)
return -EOPNOTSUPP;
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_DAT)
return -EOPNOTSUPP;
/* we must resolve the address without holding the mmap semaphore.
* This is ok since the userspace hypervisor is not supposed to change
* the mapping while the guest queries the memory. Otherwise the guest
* might crash or get wrong info anyway. */
user_address = (unsigned long) __guestaddr_to_user(vcpu, address1);
down_read(&current->mm->mmap_sem);
vma = find_vma(current->mm, user_address);
if (!vma) {
up_read(&current->mm->mmap_sem);
return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
}
vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
if (!(vma->vm_flags & VM_WRITE) && (vma->vm_flags & VM_READ))
vcpu->arch.sie_block->gpsw.mask |= (1ul << 44);
if (!(vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_READ))
vcpu->arch.sie_block->gpsw.mask |= (2ul << 44);
up_read(&current->mm->mmap_sem);
return 0;
}
int kvm_s390_handle_e5(struct kvm_vcpu *vcpu)
{
/* For e5xx... instructions we only handle TPROT */
if ((vcpu->arch.sie_block->ipa & 0x00ff) == 0x01)
return handle_tprot(vcpu);
return -EOPNOTSUPP;
}
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