Commit a31b50d7 authored by James Hogan's avatar James Hogan
Browse files

KVM: MIPS/MMU: Invalidate GVA PTs on ASID changes 



Implement invalidation of large ranges of virtual addresses from GVA
page tables in response to a guest ASID change (immediately for guest
kernel page table, lazily for guest user page table).

We iterate through a range of page tables invalidating entries and
freeing fully invalidated tables. To minimise overhead the exact ranges
invalidated depends on the flags argument to kvm_mips_flush_gva_pt(),
which also allows it to be used in future KVM_CAP_SYNC_MMU patches in
response to GPA changes, which unlike guest TLB mapping changes affects
guest KSeg0 mappings.

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
parent 57e3869c

arch/mips/include/asm/kvm_host.h

+17 −0
Original line number Diff line number Diff line
@@ -614,6 +614,23 @@ extern int kvm_mips_host_tlb_lookup(struct kvm_vcpu *vcpu, unsigned long vaddr); 
void kvm_mips_suspend_mm(int cpu);

void kvm_mips_resume_mm(int cpu);



/* MMU handling */



/**

 * enum kvm_mips_flush - Types of MMU flushes.

 * @KMF_USER:	Flush guest user virtual memory mappings.

 *		Guest USeg only.

 * @KMF_KERN:	Flush guest kernel virtual memory mappings.

 *		Guest USeg and KSeg2/3.

 * @KMF_GPA:	Flush guest physical memory mappings.

 *		Also includes KSeg0 if KMF_KERN is set.

 */

enum kvm_mips_flush {

	KMF_USER	= 0x0,

	KMF_KERN	= 0x1,

	KMF_GPA		= 0x2,

};

void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags);

extern unsigned long kvm_mips_translate_guest_kseg0_to_hpa(struct kvm_vcpu *vcpu,

						   unsigned long gva);

extern void kvm_get_new_mmu_context(struct mm_struct *mm, unsigned long cpu,

arch/mips/kvm/emulate.c

+11 −0
Original line number Diff line number Diff line
@@ -1171,6 +1171,17 @@ enum emulation_result kvm_mips_emulate_CP0(union mips_instruction inst, 
							& KVM_ENTRYHI_ASID,

						nasid);



					/*

					 * Flush entries from the GVA page

					 * tables.

					 * Guest user page table will get

					 * flushed lazily on re-entry to guest

					 * user if the guest ASID actually

					 * changes.

					 */

					kvm_mips_flush_gva_pt(kern_mm->pgd,

							      KMF_KERN);



					/*

					 * Regenerate/invalidate kernel MMU

					 * context.

arch/mips/kvm/mmu.c

+134 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/highmem.h>

#include <linux/kvm_host.h>

#include <asm/mmu_context.h>

#include <asm/pgalloc.h>



static u32 kvm_mips_get_kernel_asid(struct kvm_vcpu *vcpu)

{
@@ -80,6 +81,139 @@ unsigned long kvm_mips_translate_guest_kseg0_to_hpa(struct kvm_vcpu *vcpu, 
	return (kvm->arch.guest_pmap[gfn] << PAGE_SHIFT) + offset;

}



/*

 * kvm_mips_flush_gva_{pte,pmd,pud,pgd,pt}.

 * Flush a range of guest physical address space from the VM's GPA page tables.

 */



static bool kvm_mips_flush_gva_pte(pte_t *pte, unsigned long start_gva,

				   unsigned long end_gva)

{

	int i_min = __pte_offset(start_gva);

	int i_max = __pte_offset(end_gva);

	bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);

	int i;



	/*

	 * There's no freeing to do, so there's no point clearing individual

	 * entries unless only part of the last level page table needs flushing.

	 */

	if (safe_to_remove)

		return true;



	for (i = i_min; i <= i_max; ++i) {

		if (!pte_present(pte[i]))

			continue;



		set_pte(pte + i, __pte(0));

	}

	return false;

}



static bool kvm_mips_flush_gva_pmd(pmd_t *pmd, unsigned long start_gva,

				   unsigned long end_gva)

{

	pte_t *pte;

	unsigned long end = ~0ul;

	int i_min = __pmd_offset(start_gva);

	int i_max = __pmd_offset(end_gva);

	bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);

	int i;



	for (i = i_min; i <= i_max; ++i, start_gva = 0) {

		if (!pmd_present(pmd[i]))

			continue;



		pte = pte_offset(pmd + i, 0);

		if (i == i_max)

			end = end_gva;



		if (kvm_mips_flush_gva_pte(pte, start_gva, end)) {

			pmd_clear(pmd + i);

			pte_free_kernel(NULL, pte);

		} else {

			safe_to_remove = false;

		}

	}

	return safe_to_remove;

}



static bool kvm_mips_flush_gva_pud(pud_t *pud, unsigned long start_gva,

				   unsigned long end_gva)

{

	pmd_t *pmd;

	unsigned long end = ~0ul;

	int i_min = __pud_offset(start_gva);

	int i_max = __pud_offset(end_gva);

	bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);

	int i;



	for (i = i_min; i <= i_max; ++i, start_gva = 0) {

		if (!pud_present(pud[i]))

			continue;



		pmd = pmd_offset(pud + i, 0);

		if (i == i_max)

			end = end_gva;



		if (kvm_mips_flush_gva_pmd(pmd, start_gva, end)) {

			pud_clear(pud + i);

			pmd_free(NULL, pmd);

		} else {

			safe_to_remove = false;

		}

	}

	return safe_to_remove;

}



static bool kvm_mips_flush_gva_pgd(pgd_t *pgd, unsigned long start_gva,

				   unsigned long end_gva)

{

	pud_t *pud;

	unsigned long end = ~0ul;

	int i_min = pgd_index(start_gva);

	int i_max = pgd_index(end_gva);

	bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);

	int i;



	for (i = i_min; i <= i_max; ++i, start_gva = 0) {

		if (!pgd_present(pgd[i]))

			continue;



		pud = pud_offset(pgd + i, 0);

		if (i == i_max)

			end = end_gva;



		if (kvm_mips_flush_gva_pud(pud, start_gva, end)) {

			pgd_clear(pgd + i);

			pud_free(NULL, pud);

		} else {

			safe_to_remove = false;

		}

	}

	return safe_to_remove;

}



void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags)

{

	if (flags & KMF_GPA) {

		/* all of guest virtual address space could be affected */

		if (flags & KMF_KERN)

			/* useg, kseg0, seg2/3 */

			kvm_mips_flush_gva_pgd(pgd, 0, 0x7fffffff);

		else

			/* useg */

			kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);

	} else {

		/* useg */

		kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);



		/* kseg2/3 */

		if (flags & KMF_KERN)

			kvm_mips_flush_gva_pgd(pgd, 0x60000000, 0x7fffffff);

	}

}



/* XXXKYMA: Must be called with interrupts disabled */

int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,

				    struct kvm_vcpu *vcpu)

arch/mips/kvm/trap_emul.c

+3 −2
Original line number Diff line number Diff line
@@ -774,14 +774,15 @@ static void kvm_trap_emul_vcpu_reenter(struct kvm_run *run, 
	unsigned int gasid;



	/*

	 * Lazy host ASID regeneration for guest user mode.

	 * Lazy host ASID regeneration / PT flush for guest user mode.

	 * If the guest ASID has changed since the last guest usermode

	 * execution, regenerate the host ASID so as to invalidate stale TLB

	 * entries.

	 * entries and flush GVA PT entries too.

	 */

	if (!KVM_GUEST_KERNEL_MODE(vcpu)) {

		gasid = kvm_read_c0_guest_entryhi(cop0) & KVM_ENTRYHI_ASID;

		if (gasid != vcpu->arch.last_user_gasid) {

			kvm_mips_flush_gva_pt(user_mm->pgd, KMF_USER);

			kvm_get_new_mmu_context(user_mm, cpu, vcpu);

			for_each_possible_cpu(i)

				if (i != cpu)