fe4e771d5c
We used to defer invalidating userspace TLB entries until jumping out of the kernel. This was causing MMU weirdness most easily triggered by using a pipe in the guest, e.g. "dmesg | tail". I believe the problem was that after the guest kernel changed the PID (part of context switch), the old process's mappings were still present, and so copy_to_user() on the "return to new process" path ended up using stale mappings. Testing with large pages (64K) exposed the problem, probably because with 4K pages, pressure on the TLB faulted all process A's mappings out before the guest kernel could insert any for process B. Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
407 lines
10 KiB
C
407 lines
10 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* Copyright IBM Corp. 2007
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*
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* Authors: Hollis Blanchard <hollisb@us.ibm.com>
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*/
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/kvm.h>
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#include <linux/kvm_host.h>
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#include <linux/highmem.h>
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#include <asm/mmu-44x.h>
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#include <asm/kvm_ppc.h>
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#include <asm/kvm_44x.h>
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#include "44x_tlb.h"
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#define PPC44x_TLB_UATTR_MASK \
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(PPC44x_TLB_U0|PPC44x_TLB_U1|PPC44x_TLB_U2|PPC44x_TLB_U3)
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#define PPC44x_TLB_USER_PERM_MASK (PPC44x_TLB_UX|PPC44x_TLB_UR|PPC44x_TLB_UW)
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#define PPC44x_TLB_SUPER_PERM_MASK (PPC44x_TLB_SX|PPC44x_TLB_SR|PPC44x_TLB_SW)
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static unsigned int kvmppc_tlb_44x_pos;
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#ifdef DEBUG
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void kvmppc_dump_tlbs(struct kvm_vcpu *vcpu)
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{
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struct kvmppc_44x_tlbe *tlbe;
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int i;
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printk("vcpu %d TLB dump:\n", vcpu->vcpu_id);
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printk("| %2s | %3s | %8s | %8s | %8s |\n",
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"nr", "tid", "word0", "word1", "word2");
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for (i = 0; i < PPC44x_TLB_SIZE; i++) {
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tlbe = &vcpu_44x->guest_tlb[i];
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if (tlbe->word0 & PPC44x_TLB_VALID)
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printk(" G%2d | %02X | %08X | %08X | %08X |\n",
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i, tlbe->tid, tlbe->word0, tlbe->word1,
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tlbe->word2);
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}
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for (i = 0; i < PPC44x_TLB_SIZE; i++) {
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tlbe = &vcpu_44x->shadow_tlb[i];
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if (tlbe->word0 & PPC44x_TLB_VALID)
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printk(" S%2d | %02X | %08X | %08X | %08X |\n",
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i, tlbe->tid, tlbe->word0, tlbe->word1,
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tlbe->word2);
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}
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}
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#endif
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static u32 kvmppc_44x_tlb_shadow_attrib(u32 attrib, int usermode)
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{
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/* We only care about the guest's permission and user bits. */
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attrib &= PPC44x_TLB_PERM_MASK|PPC44x_TLB_UATTR_MASK;
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if (!usermode) {
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/* Guest is in supervisor mode, so we need to translate guest
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* supervisor permissions into user permissions. */
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attrib &= ~PPC44x_TLB_USER_PERM_MASK;
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attrib |= (attrib & PPC44x_TLB_SUPER_PERM_MASK) << 3;
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}
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/* Make sure host can always access this memory. */
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attrib |= PPC44x_TLB_SX|PPC44x_TLB_SR|PPC44x_TLB_SW;
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/* WIMGE = 0b00100 */
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attrib |= PPC44x_TLB_M;
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return attrib;
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}
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/* Search the guest TLB for a matching entry. */
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int kvmppc_44x_tlb_index(struct kvm_vcpu *vcpu, gva_t eaddr, unsigned int pid,
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unsigned int as)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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int i;
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/* XXX Replace loop with fancy data structures. */
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for (i = 0; i < PPC44x_TLB_SIZE; i++) {
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struct kvmppc_44x_tlbe *tlbe = &vcpu_44x->guest_tlb[i];
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unsigned int tid;
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if (eaddr < get_tlb_eaddr(tlbe))
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continue;
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if (eaddr > get_tlb_end(tlbe))
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continue;
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tid = get_tlb_tid(tlbe);
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if (tid && (tid != pid))
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continue;
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if (!get_tlb_v(tlbe))
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continue;
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if (get_tlb_ts(tlbe) != as)
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continue;
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return i;
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}
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return -1;
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}
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struct kvmppc_44x_tlbe *kvmppc_44x_itlb_search(struct kvm_vcpu *vcpu,
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gva_t eaddr)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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unsigned int as = !!(vcpu->arch.msr & MSR_IS);
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unsigned int index;
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index = kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
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if (index == -1)
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return NULL;
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return &vcpu_44x->guest_tlb[index];
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}
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struct kvmppc_44x_tlbe *kvmppc_44x_dtlb_search(struct kvm_vcpu *vcpu,
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gva_t eaddr)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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unsigned int as = !!(vcpu->arch.msr & MSR_DS);
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unsigned int index;
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index = kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
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if (index == -1)
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return NULL;
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return &vcpu_44x->guest_tlb[index];
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}
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static int kvmppc_44x_tlbe_is_writable(struct kvmppc_44x_tlbe *tlbe)
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{
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return tlbe->word2 & (PPC44x_TLB_SW|PPC44x_TLB_UW);
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}
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static void kvmppc_44x_shadow_release(struct kvm_vcpu *vcpu,
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unsigned int index)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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struct kvmppc_44x_tlbe *stlbe = &vcpu_44x->shadow_tlb[index];
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struct page *page = vcpu_44x->shadow_pages[index];
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if (get_tlb_v(stlbe)) {
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if (kvmppc_44x_tlbe_is_writable(stlbe))
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kvm_release_page_dirty(page);
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else
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kvm_release_page_clean(page);
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}
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}
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void kvmppc_core_destroy_mmu(struct kvm_vcpu *vcpu)
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{
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int i;
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for (i = 0; i <= tlb_44x_hwater; i++)
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kvmppc_44x_shadow_release(vcpu, i);
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}
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void kvmppc_tlbe_set_modified(struct kvm_vcpu *vcpu, unsigned int i)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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vcpu_44x->shadow_tlb_mod[i] = 1;
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}
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/* Caller must ensure that the specified guest TLB entry is safe to insert into
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* the shadow TLB. */
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void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 gvaddr, gfn_t gfn, u64 asid,
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u32 flags)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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struct page *new_page;
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struct kvmppc_44x_tlbe *stlbe;
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hpa_t hpaddr;
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unsigned int victim;
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/* Future optimization: don't overwrite the TLB entry containing the
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* current PC (or stack?). */
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victim = kvmppc_tlb_44x_pos++;
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if (kvmppc_tlb_44x_pos > tlb_44x_hwater)
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kvmppc_tlb_44x_pos = 0;
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stlbe = &vcpu_44x->shadow_tlb[victim];
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/* Get reference to new page. */
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new_page = gfn_to_page(vcpu->kvm, gfn);
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if (is_error_page(new_page)) {
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printk(KERN_ERR "Couldn't get guest page for gfn %lx!\n", gfn);
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kvm_release_page_clean(new_page);
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return;
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}
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hpaddr = page_to_phys(new_page);
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/* Drop reference to old page. */
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kvmppc_44x_shadow_release(vcpu, victim);
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vcpu_44x->shadow_pages[victim] = new_page;
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/* XXX Make sure (va, size) doesn't overlap any other
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* entries. 440x6 user manual says the result would be
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* "undefined." */
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/* XXX what about AS? */
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stlbe->tid = !(asid & 0xff);
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/* Force TS=1 for all guest mappings. */
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/* For now we hardcode 4KB mappings, but it will be important to
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* use host large pages in the future. */
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stlbe->word0 = (gvaddr & PAGE_MASK) | PPC44x_TLB_VALID | PPC44x_TLB_TS
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| PPC44x_TLB_4K;
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stlbe->word1 = (hpaddr & 0xfffffc00) | ((hpaddr >> 32) & 0xf);
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stlbe->word2 = kvmppc_44x_tlb_shadow_attrib(flags,
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vcpu->arch.msr & MSR_PR);
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kvmppc_tlbe_set_modified(vcpu, victim);
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KVMTRACE_5D(STLB_WRITE, vcpu, victim,
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stlbe->tid, stlbe->word0, stlbe->word1, stlbe->word2,
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handler);
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}
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static void kvmppc_mmu_invalidate(struct kvm_vcpu *vcpu, gva_t eaddr,
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gva_t eend, u32 asid)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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unsigned int pid = !(asid & 0xff);
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int i;
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/* XXX Replace loop with fancy data structures. */
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for (i = 0; i <= tlb_44x_hwater; i++) {
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struct kvmppc_44x_tlbe *stlbe = &vcpu_44x->shadow_tlb[i];
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unsigned int tid;
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if (!get_tlb_v(stlbe))
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continue;
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if (eend < get_tlb_eaddr(stlbe))
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continue;
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if (eaddr > get_tlb_end(stlbe))
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continue;
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tid = get_tlb_tid(stlbe);
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if (tid && (tid != pid))
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continue;
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kvmppc_44x_shadow_release(vcpu, i);
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stlbe->word0 = 0;
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kvmppc_tlbe_set_modified(vcpu, i);
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KVMTRACE_5D(STLB_INVAL, vcpu, i,
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stlbe->tid, stlbe->word0, stlbe->word1,
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stlbe->word2, handler);
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}
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}
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void kvmppc_mmu_priv_switch(struct kvm_vcpu *vcpu, int usermode)
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{
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vcpu->arch.shadow_pid = !usermode;
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}
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void kvmppc_set_pid(struct kvm_vcpu *vcpu, u32 new_pid)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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int i;
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if (unlikely(vcpu->arch.pid == new_pid))
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return;
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vcpu->arch.pid = new_pid;
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/* Guest userspace runs with TID=0 mappings and PID=0, to make sure it
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* can't access guest kernel mappings (TID=1). When we switch to a new
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* guest PID, which will also use host PID=0, we must discard the old guest
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* userspace mappings. */
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for (i = 0; i < ARRAY_SIZE(vcpu_44x->shadow_tlb); i++) {
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struct kvmppc_44x_tlbe *stlbe = &vcpu_44x->shadow_tlb[i];
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if (get_tlb_tid(stlbe) == 0) {
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kvmppc_44x_shadow_release(vcpu, i);
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stlbe->word0 = 0;
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kvmppc_tlbe_set_modified(vcpu, i);
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}
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}
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}
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static int tlbe_is_host_safe(const struct kvm_vcpu *vcpu,
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const struct kvmppc_44x_tlbe *tlbe)
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{
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gpa_t gpa;
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if (!get_tlb_v(tlbe))
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return 0;
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/* Does it match current guest AS? */
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/* XXX what about IS != DS? */
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if (get_tlb_ts(tlbe) != !!(vcpu->arch.msr & MSR_IS))
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return 0;
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gpa = get_tlb_raddr(tlbe);
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if (!gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT))
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/* Mapping is not for RAM. */
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return 0;
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return 1;
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}
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int kvmppc_44x_emul_tlbwe(struct kvm_vcpu *vcpu, u8 ra, u8 rs, u8 ws)
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{
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struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
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u64 eaddr;
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u64 raddr;
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u64 asid;
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u32 flags;
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struct kvmppc_44x_tlbe *tlbe;
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unsigned int index;
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index = vcpu->arch.gpr[ra];
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if (index > PPC44x_TLB_SIZE) {
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printk("%s: index %d\n", __func__, index);
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kvmppc_dump_vcpu(vcpu);
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return EMULATE_FAIL;
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}
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tlbe = &vcpu_44x->guest_tlb[index];
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/* Invalidate shadow mappings for the about-to-be-clobbered TLBE. */
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if (tlbe->word0 & PPC44x_TLB_VALID) {
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eaddr = get_tlb_eaddr(tlbe);
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asid = (tlbe->word0 & PPC44x_TLB_TS) | tlbe->tid;
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kvmppc_mmu_invalidate(vcpu, eaddr, get_tlb_end(tlbe), asid);
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}
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switch (ws) {
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case PPC44x_TLB_PAGEID:
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tlbe->tid = get_mmucr_stid(vcpu);
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tlbe->word0 = vcpu->arch.gpr[rs];
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break;
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case PPC44x_TLB_XLAT:
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tlbe->word1 = vcpu->arch.gpr[rs];
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break;
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case PPC44x_TLB_ATTRIB:
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tlbe->word2 = vcpu->arch.gpr[rs];
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break;
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default:
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return EMULATE_FAIL;
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}
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if (tlbe_is_host_safe(vcpu, tlbe)) {
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eaddr = get_tlb_eaddr(tlbe);
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raddr = get_tlb_raddr(tlbe);
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asid = (tlbe->word0 & PPC44x_TLB_TS) | tlbe->tid;
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flags = tlbe->word2 & 0xffff;
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/* Create a 4KB mapping on the host. If the guest wanted a
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* large page, only the first 4KB is mapped here and the rest
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* are mapped on the fly. */
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kvmppc_mmu_map(vcpu, eaddr, raddr >> PAGE_SHIFT, asid, flags);
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}
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KVMTRACE_5D(GTLB_WRITE, vcpu, index,
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tlbe->tid, tlbe->word0, tlbe->word1, tlbe->word2,
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handler);
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return EMULATE_DONE;
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}
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int kvmppc_44x_emul_tlbsx(struct kvm_vcpu *vcpu, u8 rt, u8 ra, u8 rb, u8 rc)
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{
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u32 ea;
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int index;
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unsigned int as = get_mmucr_sts(vcpu);
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unsigned int pid = get_mmucr_stid(vcpu);
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ea = vcpu->arch.gpr[rb];
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if (ra)
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ea += vcpu->arch.gpr[ra];
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index = kvmppc_44x_tlb_index(vcpu, ea, pid, as);
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if (rc) {
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if (index < 0)
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vcpu->arch.cr &= ~0x20000000;
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else
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vcpu->arch.cr |= 0x20000000;
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}
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vcpu->arch.gpr[rt] = index;
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return EMULATE_DONE;
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}
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