* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-05-28 14:22 [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range Christoffer Dall
@ 2014-06-02 8:26 ` Jungseok Lee
2014-06-04 13:16 ` Christoffer Dall
2014-06-02 17:29 ` Mario Smarduch
2014-06-03 13:52 ` Steve Capper
2 siblings, 1 reply; 10+ messages in thread
From: Jungseok Lee @ 2014-06-02 8:26 UTC (permalink / raw)
To: linux-arm-kernel
On Wednesday, May 28, 2014 11:23 PM, Christoffer Dall wrote:
> unmap_range() was utterly broken, to quote Marc, and broke in all sorts
> of situations. It was also quite complicated to follow and didn't
> follow the usual scheme of having a separate iterating function for each
> level of page tables.
>
> Address this by refactoring the code and introduce a pgd_clear()
> function.
>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> Changes since v2:
> - Don't define custom __unused but reuse __maybe_unused
>
> arch/arm/include/asm/kvm_mmu.h | 12 ++++
> arch/arm/kvm/mmu.c | 122 ++++++++++++++++++++++-----------------
> arch/arm64/include/asm/kvm_mmu.h | 15 +++++
> 3 files changed, 95 insertions(+), 54 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 5c7aa3c..5cc0b0f 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -127,6 +127,18 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> (__boundary - 1 < (end) - 1)? __boundary: (end); \
> })
>
> +static inline bool kvm_page_empty(void *ptr)
> +{
> + struct page *ptr_page = virt_to_page(ptr);
> + return page_count(ptr_page) == 1;
> +}
> +
> +
> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> +#define kvm_pud_table_empty(pudp) (0)
> +
> +
> struct kvm;
>
> #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 16f8049..6ee6e06 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -90,10 +90,13 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> return p;
> }
>
> -static bool page_empty(void *ptr)
> +static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
> {
> - struct page *ptr_page = virt_to_page(ptr);
> - return page_count(ptr_page) == 1;
> + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
> + pgd_clear(pgd);
> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> + pud_free(NULL, pud_table);
> + put_page(virt_to_page(pgd));
> }
>
> static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> @@ -124,70 +127,81 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
> put_page(virt_to_page(pmd));
> }
>
> -static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
> +static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
> + unsigned long long addr, unsigned long long end)
> {
> - if (pte_present(*pte)) {
> - kvm_set_pte(pte, __pte(0));
> - put_page(virt_to_page(pte));
> - kvm_tlb_flush_vmid_ipa(kvm, addr);
> - }
> + pte_t *pte, *start_pte;
> + unsigned long long start_addr = addr;
> +
> + start_pte = pte = pte_offset_kernel(pmd, addr);
> + do {
> + if (!pte_none(*pte)) {
> + kvm_set_pte(pte, __pte(0));
> + put_page(virt_to_page(pte));
> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> + }
> + } while (pte++, addr += PAGE_SIZE, addr != end);
> +
> + if (kvm_pte_table_empty(start_pte))
> + clear_pmd_entry(kvm, pmd, start_addr);
> }
>
> -static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> - unsigned long long start, u64 size)
> +static void unmap_pmds(struct kvm *kvm, pud_t *pud,
> + unsigned long long addr, unsigned long long end)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> - pmd_t *pmd;
> - pte_t *pte;
> - unsigned long long addr = start, end = start + size;
> - u64 next;
> -
> - while (addr < end) {
> - pgd = pgdp + pgd_index(addr);
> - pud = pud_offset(pgd, addr);
> - pte = NULL;
> - if (pud_none(*pud)) {
> - addr = kvm_pud_addr_end(addr, end);
> - continue;
> - }
> + unsigned long long next, start_addr = addr;
> + pmd_t *pmd, *start_pmd;
>
> - if (pud_huge(*pud)) {
> - /*
> - * If we are dealing with a huge pud, just clear it and
> - * move on.
> - */
> - clear_pud_entry(kvm, pud, addr);
> - addr = kvm_pud_addr_end(addr, end);
> - continue;
> + start_pmd = pmd = pmd_offset(pud, addr);
> + do {
> + next = kvm_pmd_addr_end(addr, end);
> + if (!pmd_none(*pmd)) {
> + if (kvm_pmd_huge(*pmd))
> + clear_pmd_entry(kvm, pmd, addr);
> + else
> + unmap_ptes(kvm, pmd, addr, next);
> }
> + } while (pmd++, addr = next, addr != end);
>
> - pmd = pmd_offset(pud, addr);
> - if (pmd_none(*pmd)) {
> - addr = kvm_pmd_addr_end(addr, end);
> - continue;
> - }
> + if (kvm_pmd_table_empty(start_pmd))
> + clear_pud_entry(kvm, pud, start_addr);
> +}
>
> - if (!kvm_pmd_huge(*pmd)) {
> - pte = pte_offset_kernel(pmd, addr);
> - clear_pte_entry(kvm, pte, addr);
> - next = addr + PAGE_SIZE;
> - }
> +static void unmap_puds(struct kvm *kvm, pgd_t *pgd,
> + unsigned long long addr, unsigned long long end)
> +{
> + unsigned long long next, start_addr = addr;
> + pud_t *pud, *start_pud;
>
> - /*
> - * If the pmd entry is to be cleared, walk back up the ladder
> - */
> - if (kvm_pmd_huge(*pmd) || (pte && page_empty(pte))) {
> - clear_pmd_entry(kvm, pmd, addr);
> - next = kvm_pmd_addr_end(addr, end);
> - if (page_empty(pmd) && !page_empty(pud)) {
> + start_pud = pud = pud_offset(pgd, addr);
> + do {
> + next = kvm_pud_addr_end(addr, end);
> + if (!pud_none(*pud)) {
> + if (pud_huge(*pid)) {
> clear_pud_entry(kvm, pud, addr);
> - next = kvm_pud_addr_end(addr, end);
> + } else {
> + unmap_pmds(kvm, pud, addr, next);
> }
> }
> + } while (pud++, addr = next, addr != end);
>
> - addr = next;
> - }
> + if (kvm_pud_table_empty(start_pud))
> + clear_pgd_entry(kvm, pgd, start_addr);
> +}
> +
> +
> +static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> + unsigned long long start, u64 size)
> +{
> + pgd_t *pgd;
> + unsigned long long addr = start, end = start + size;
> + unsigned long long next;
> +
> + pgd = pgdp + pgd_index(addr);
> + do {
> + next = kvm_pgd_addr_end(addr, end);
> + unmap_puds(kvm, pgd, addr, next);
> + } while (pgd++, addr = next, addr != end);
> }
>
> static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 7d29847..8e138c7 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -125,6 +125,21 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> #define kvm_pud_addr_end(addr, end) pud_addr_end(addr, end)
> #define kvm_pmd_addr_end(addr, end) pmd_addr_end(addr, end)
>
> +static inline bool kvm_page_empty(void *ptr)
> +{
> + struct page *ptr_page = virt_to_page(ptr);
> + return page_count(ptr_page) == 1;
> +}
> +
> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> +#ifndef CONFIG_ARM64_64K_PAGES
> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> +#else
> +#define kvm_pmd_table_empty(pmdp) (0)
> +#endif
> +#define kvm_pud_table_empty(pudp) (0)
> +
> +
This is a pretty good idea. It helps to accommodate different translation
level options supported by ARMv8.
It looks reasonable to me:
Reviewed-by: Jungseok Lee <jays.lee@samsung.com>
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-05-28 14:22 [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range Christoffer Dall
2014-06-02 8:26 ` Jungseok Lee
@ 2014-06-02 17:29 ` Mario Smarduch
2014-06-04 13:22 ` Christoffer Dall
2014-06-03 13:52 ` Steve Capper
2 siblings, 1 reply; 10+ messages in thread
From: Mario Smarduch @ 2014-06-02 17:29 UTC (permalink / raw)
To: linux-arm-kernel
On 05/28/2014 07:22 AM, Christoffer Dall wrote:
> unmap_range() was utterly broken, to quote Marc, and broke in all sorts
> of situations. It was also quite complicated to follow and didn't
> follow the usual scheme of having a separate iterating function for each
> level of page tables.
>
> Address this by refactoring the code and introduce a pgd_clear()
> function.
>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> Changes since v2:
> - Don't define custom __unused but reuse __maybe_unused
>
> arch/arm/include/asm/kvm_mmu.h | 12 ++++
> arch/arm/kvm/mmu.c | 122 ++++++++++++++++++++++-----------------
> arch/arm64/include/asm/kvm_mmu.h | 15 +++++
> 3 files changed, 95 insertions(+), 54 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 5c7aa3c..5cc0b0f 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -127,6 +127,18 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> (__boundary - 1 < (end) - 1)? __boundary: (end); \
> })
>
> +static inline bool kvm_page_empty(void *ptr)
> +{
> + struct page *ptr_page = virt_to_page(ptr);
> + return page_count(ptr_page) == 1;
> +}
> +
> +
> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> +#define kvm_pud_table_empty(pudp) (0)
> +
> +
> struct kvm;
>
> #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 16f8049..6ee6e06 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -90,10 +90,13 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> return p;
> }
>
> -static bool page_empty(void *ptr)
> +static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
> {
> - struct page *ptr_page = virt_to_page(ptr);
> - return page_count(ptr_page) == 1;
> + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
> + pgd_clear(pgd);
> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> + pud_free(NULL, pud_table);
> + put_page(virt_to_page(pgd));
> }
>
> static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> @@ -124,70 +127,81 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
> put_page(virt_to_page(pmd));
> }
>
> -static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
> +static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
> + unsigned long long addr, unsigned long long end)
> {
> - if (pte_present(*pte)) {
> - kvm_set_pte(pte, __pte(0));
> - put_page(virt_to_page(pte));
> - kvm_tlb_flush_vmid_ipa(kvm, addr);
> - }
> + pte_t *pte, *start_pte;
> + unsigned long long start_addr = addr;
> +
> + start_pte = pte = pte_offset_kernel(pmd, addr);
> + do {
> + if (!pte_none(*pte)) {
> + kvm_set_pte(pte, __pte(0));
> + put_page(virt_to_page(pte));
> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> + }
> + } while (pte++, addr += PAGE_SIZE, addr != end);
> +
> + if (kvm_pte_table_empty(start_pte))
> + clear_pmd_entry(kvm, pmd, start_addr);
> }
>
> -static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> - unsigned long long start, u64 size)
> +static void unmap_pmds(struct kvm *kvm, pud_t *pud,
> + unsigned long long addr, unsigned long long end)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> - pmd_t *pmd;
> - pte_t *pte;
> - unsigned long long addr = start, end = start + size;
> - u64 next;
> -
> - while (addr < end) {
> - pgd = pgdp + pgd_index(addr);
> - pud = pud_offset(pgd, addr);
> - pte = NULL;
> - if (pud_none(*pud)) {
> - addr = kvm_pud_addr_end(addr, end);
> - continue;
> - }
> + unsigned long long next, start_addr = addr;
> + pmd_t *pmd, *start_pmd;
>
> - if (pud_huge(*pud)) {
> - /*
> - * If we are dealing with a huge pud, just clear it and
> - * move on.
> - */
> - clear_pud_entry(kvm, pud, addr);
> - addr = kvm_pud_addr_end(addr, end);
> - continue;
> + start_pmd = pmd = pmd_offset(pud, addr);
> + do {
> + next = kvm_pmd_addr_end(addr, end);
> + if (!pmd_none(*pmd)) {
> + if (kvm_pmd_huge(*pmd))
> + clear_pmd_entry(kvm, pmd, addr);
> + else
> + unmap_ptes(kvm, pmd, addr, next);
> }
> + } while (pmd++, addr = next, addr != end);
>
> - pmd = pmd_offset(pud, addr);
> - if (pmd_none(*pmd)) {
> - addr = kvm_pmd_addr_end(addr, end);
> - continue;
> - }
> + if (kvm_pmd_table_empty(start_pmd))
> + clear_pud_entry(kvm, pud, start_addr);
> +}
>
> - if (!kvm_pmd_huge(*pmd)) {
> - pte = pte_offset_kernel(pmd, addr);
> - clear_pte_entry(kvm, pte, addr);
> - next = addr + PAGE_SIZE;
> - }
> +static void unmap_puds(struct kvm *kvm, pgd_t *pgd,
> + unsigned long long addr, unsigned long long end)
> +{
> + unsigned long long next, start_addr = addr;
> + pud_t *pud, *start_pud;
>
> - /*
> - * If the pmd entry is to be cleared, walk back up the ladder
> - */
> - if (kvm_pmd_huge(*pmd) || (pte && page_empty(pte))) {
> - clear_pmd_entry(kvm, pmd, addr);
> - next = kvm_pmd_addr_end(addr, end);
> - if (page_empty(pmd) && !page_empty(pud)) {
> + start_pud = pud = pud_offset(pgd, addr);
> + do {
> + next = kvm_pud_addr_end(addr, end);
> + if (!pud_none(*pud)) {
> + if (pud_huge(*pid)) {
The *pid breaks build, assuming *pud here.
> clear_pud_entry(kvm, pud, addr);
> - next = kvm_pud_addr_end(addr, end);
> + } else {
> + unmap_pmds(kvm, pud, addr, next);
> }
I minor one but I figure I mention it, checkpatch.pl complains
about the unnecessary braces
> }
> + } while (pud++, addr = next, addr != end);
>
> - addr = next;
> - }
> + if (kvm_pud_table_empty(start_pud))
> + clear_pgd_entry(kvm, pgd, start_addr);
> +}
> +
> +
> +static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> + unsigned long long start, u64 size)
> +{
> + pgd_t *pgd;
> + unsigned long long addr = start, end = start + size;
> + unsigned long long next;
> +
> + pgd = pgdp + pgd_index(addr);
> + do {
> + next = kvm_pgd_addr_end(addr, end);
> + unmap_puds(kvm, pgd, addr, next);
> + } while (pgd++, addr = next, addr != end);
> }
>
> static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 7d29847..8e138c7 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -125,6 +125,21 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> #define kvm_pud_addr_end(addr, end) pud_addr_end(addr, end)
> #define kvm_pmd_addr_end(addr, end) pmd_addr_end(addr, end)
>
> +static inline bool kvm_page_empty(void *ptr)
> +{
> + struct page *ptr_page = virt_to_page(ptr);
> + return page_count(ptr_page) == 1;
> +}
> +
> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> +#ifndef CONFIG_ARM64_64K_PAGES
> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> +#else
> +#define kvm_pmd_table_empty(pmdp) (0)
> +#endif
> +#define kvm_pud_table_empty(pudp) (0)
> +
> +
> struct kvm;
>
> #define kvm_flush_dcache_to_poc(a,l) __flush_dcache_area((a), (l))
>
Tested on 4-way SMP with page reclaim no problem seen.
Reviewed-by: Mario Smarduch <m.smarduch@samsung.com>
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-06-02 17:29 ` Mario Smarduch
@ 2014-06-04 13:22 ` Christoffer Dall
0 siblings, 0 replies; 10+ messages in thread
From: Christoffer Dall @ 2014-06-04 13:22 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, Jun 02, 2014 at 10:29:51AM -0700, Mario Smarduch wrote:
> On 05/28/2014 07:22 AM, Christoffer Dall wrote:
> > unmap_range() was utterly broken, to quote Marc, and broke in all sorts
> > of situations. It was also quite complicated to follow and didn't
> > follow the usual scheme of having a separate iterating function for each
> > level of page tables.
> >
> > Address this by refactoring the code and introduce a pgd_clear()
> > function.
> >
> > Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> > ---
> > Changes since v2:
> > - Don't define custom __unused but reuse __maybe_unused
> >
> > arch/arm/include/asm/kvm_mmu.h | 12 ++++
> > arch/arm/kvm/mmu.c | 122 ++++++++++++++++++++++-----------------
> > arch/arm64/include/asm/kvm_mmu.h | 15 +++++
> > 3 files changed, 95 insertions(+), 54 deletions(-)
> >
> > diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> > index 5c7aa3c..5cc0b0f 100644
> > --- a/arch/arm/include/asm/kvm_mmu.h
> > +++ b/arch/arm/include/asm/kvm_mmu.h
> > @@ -127,6 +127,18 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> > (__boundary - 1 < (end) - 1)? __boundary: (end); \
> > })
> >
> > +static inline bool kvm_page_empty(void *ptr)
> > +{
> > + struct page *ptr_page = virt_to_page(ptr);
> > + return page_count(ptr_page) == 1;
> > +}
> > +
> > +
> > +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> > +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> > +#define kvm_pud_table_empty(pudp) (0)
> > +
> > +
> > struct kvm;
> >
> > #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> > index 16f8049..6ee6e06 100644
> > --- a/arch/arm/kvm/mmu.c
> > +++ b/arch/arm/kvm/mmu.c
> > @@ -90,10 +90,13 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> > return p;
> > }
> >
> > -static bool page_empty(void *ptr)
> > +static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
> > {
> > - struct page *ptr_page = virt_to_page(ptr);
> > - return page_count(ptr_page) == 1;
> > + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
> > + pgd_clear(pgd);
> > + kvm_tlb_flush_vmid_ipa(kvm, addr);
> > + pud_free(NULL, pud_table);
> > + put_page(virt_to_page(pgd));
> > }
> >
> > static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> > @@ -124,70 +127,81 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
> > put_page(virt_to_page(pmd));
> > }
> >
> > -static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
> > +static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
> > + unsigned long long addr, unsigned long long end)
> > {
> > - if (pte_present(*pte)) {
> > - kvm_set_pte(pte, __pte(0));
> > - put_page(virt_to_page(pte));
> > - kvm_tlb_flush_vmid_ipa(kvm, addr);
> > - }
> > + pte_t *pte, *start_pte;
> > + unsigned long long start_addr = addr;
> > +
> > + start_pte = pte = pte_offset_kernel(pmd, addr);
> > + do {
> > + if (!pte_none(*pte)) {
> > + kvm_set_pte(pte, __pte(0));
> > + put_page(virt_to_page(pte));
> > + kvm_tlb_flush_vmid_ipa(kvm, addr);
> > + }
> > + } while (pte++, addr += PAGE_SIZE, addr != end);
> > +
> > + if (kvm_pte_table_empty(start_pte))
> > + clear_pmd_entry(kvm, pmd, start_addr);
> > }
> >
> > -static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> > - unsigned long long start, u64 size)
> > +static void unmap_pmds(struct kvm *kvm, pud_t *pud,
> > + unsigned long long addr, unsigned long long end)
> > {
> > - pgd_t *pgd;
> > - pud_t *pud;
> > - pmd_t *pmd;
> > - pte_t *pte;
> > - unsigned long long addr = start, end = start + size;
> > - u64 next;
> > -
> > - while (addr < end) {
> > - pgd = pgdp + pgd_index(addr);
> > - pud = pud_offset(pgd, addr);
> > - pte = NULL;
> > - if (pud_none(*pud)) {
> > - addr = kvm_pud_addr_end(addr, end);
> > - continue;
> > - }
> > + unsigned long long next, start_addr = addr;
> > + pmd_t *pmd, *start_pmd;
> >
> > - if (pud_huge(*pud)) {
> > - /*
> > - * If we are dealing with a huge pud, just clear it and
> > - * move on.
> > - */
> > - clear_pud_entry(kvm, pud, addr);
> > - addr = kvm_pud_addr_end(addr, end);
> > - continue;
> > + start_pmd = pmd = pmd_offset(pud, addr);
> > + do {
> > + next = kvm_pmd_addr_end(addr, end);
> > + if (!pmd_none(*pmd)) {
> > + if (kvm_pmd_huge(*pmd))
> > + clear_pmd_entry(kvm, pmd, addr);
> > + else
> > + unmap_ptes(kvm, pmd, addr, next);
> > }
> > + } while (pmd++, addr = next, addr != end);
> >
> > - pmd = pmd_offset(pud, addr);
> > - if (pmd_none(*pmd)) {
> > - addr = kvm_pmd_addr_end(addr, end);
> > - continue;
> > - }
> > + if (kvm_pmd_table_empty(start_pmd))
> > + clear_pud_entry(kvm, pud, start_addr);
> > +}
> >
> > - if (!kvm_pmd_huge(*pmd)) {
> > - pte = pte_offset_kernel(pmd, addr);
> > - clear_pte_entry(kvm, pte, addr);
> > - next = addr + PAGE_SIZE;
> > - }
> > +static void unmap_puds(struct kvm *kvm, pgd_t *pgd,
> > + unsigned long long addr, unsigned long long end)
> > +{
> > + unsigned long long next, start_addr = addr;
> > + pud_t *pud, *start_pud;
> >
> > - /*
> > - * If the pmd entry is to be cleared, walk back up the ladder
> > - */
> > - if (kvm_pmd_huge(*pmd) || (pte && page_empty(pte))) {
> > - clear_pmd_entry(kvm, pmd, addr);
> > - next = kvm_pmd_addr_end(addr, end);
> > - if (page_empty(pmd) && !page_empty(pud)) {
> > + start_pud = pud = pud_offset(pgd, addr);
> > + do {
> > + next = kvm_pud_addr_end(addr, end);
> > + if (!pud_none(*pud)) {
> > + if (pud_huge(*pid)) {
>
> The *pid breaks build, assuming *pud here.
>
ah, right, thanks for spotting it.
> > clear_pud_entry(kvm, pud, addr);
> > - next = kvm_pud_addr_end(addr, end);
> > + } else {
> > + unmap_pmds(kvm, pud, addr, next);
> > }
> I minor one but I figure I mention it, checkpatch.pl complains
> about the unnecessary braces
and it's right, I've corrected it.
> > }
> > + } while (pud++, addr = next, addr != end);
> >
> > - addr = next;
> > - }
> > + if (kvm_pud_table_empty(start_pud))
> > + clear_pgd_entry(kvm, pgd, start_addr);
> > +}
> > +
> > +
> > +static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> > + unsigned long long start, u64 size)
> > +{
> > + pgd_t *pgd;
> > + unsigned long long addr = start, end = start + size;
> > + unsigned long long next;
> > +
> > + pgd = pgdp + pgd_index(addr);
> > + do {
> > + next = kvm_pgd_addr_end(addr, end);
> > + unmap_puds(kvm, pgd, addr, next);
> > + } while (pgd++, addr = next, addr != end);
> > }
> >
> > static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
> > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> > index 7d29847..8e138c7 100644
> > --- a/arch/arm64/include/asm/kvm_mmu.h
> > +++ b/arch/arm64/include/asm/kvm_mmu.h
> > @@ -125,6 +125,21 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> > #define kvm_pud_addr_end(addr, end) pud_addr_end(addr, end)
> > #define kvm_pmd_addr_end(addr, end) pmd_addr_end(addr, end)
> >
> > +static inline bool kvm_page_empty(void *ptr)
> > +{
> > + struct page *ptr_page = virt_to_page(ptr);
> > + return page_count(ptr_page) == 1;
> > +}
> > +
> > +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> > +#ifndef CONFIG_ARM64_64K_PAGES
> > +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> > +#else
> > +#define kvm_pmd_table_empty(pmdp) (0)
> > +#endif
> > +#define kvm_pud_table_empty(pudp) (0)
> > +
> > +
> > struct kvm;
> >
> > #define kvm_flush_dcache_to_poc(a,l) __flush_dcache_area((a), (l))
> >
>
> Tested on 4-way SMP with page reclaim no problem seen.
>
> Reviewed-by: Mario Smarduch <m.smarduch@samsung.com>
>
Thanks,
-Christoffer
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-05-28 14:22 [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range Christoffer Dall
2014-06-02 8:26 ` Jungseok Lee
2014-06-02 17:29 ` Mario Smarduch
@ 2014-06-03 13:52 ` Steve Capper
2014-06-04 13:30 ` Christoffer Dall
2 siblings, 1 reply; 10+ messages in thread
From: Steve Capper @ 2014-06-03 13:52 UTC (permalink / raw)
To: linux-arm-kernel
Hi Christoffer,
I have some comments below:
On 28 May 2014 15:22, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> unmap_range() was utterly broken, to quote Marc, and broke in all sorts
> of situations. It was also quite complicated to follow and didn't
> follow the usual scheme of having a separate iterating function for each
> level of page tables.
>
> Address this by refactoring the code and introduce a pgd_clear()
> function.
>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> Changes since v2:
> - Don't define custom __unused but reuse __maybe_unused
>
> arch/arm/include/asm/kvm_mmu.h | 12 ++++
> arch/arm/kvm/mmu.c | 122 ++++++++++++++++++++++-----------------
> arch/arm64/include/asm/kvm_mmu.h | 15 +++++
> 3 files changed, 95 insertions(+), 54 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 5c7aa3c..5cc0b0f 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -127,6 +127,18 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> (__boundary - 1 < (end) - 1)? __boundary: (end); \
> })
>
> +static inline bool kvm_page_empty(void *ptr)
> +{
> + struct page *ptr_page = virt_to_page(ptr);
> + return page_count(ptr_page) == 1;
> +}
> +
> +
> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> +#define kvm_pud_table_empty(pudp) (0)
> +
> +
> struct kvm;
>
> #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 16f8049..6ee6e06 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -90,10 +90,13 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> return p;
> }
>
> -static bool page_empty(void *ptr)
> +static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
> {
> - struct page *ptr_page = virt_to_page(ptr);
> - return page_count(ptr_page) == 1;
> + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
> + pgd_clear(pgd);
> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> + pud_free(NULL, pud_table);
> + put_page(virt_to_page(pgd));
> }
>
> static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> @@ -124,70 +127,81 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
> put_page(virt_to_page(pmd));
> }
>
> -static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
> +static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
> + unsigned long long addr, unsigned long long end)
We have a lot of unsigned long longs in this patch, should they not be
phys_addr_t instead?
> {
> - if (pte_present(*pte)) {
> - kvm_set_pte(pte, __pte(0));
> - put_page(virt_to_page(pte));
> - kvm_tlb_flush_vmid_ipa(kvm, addr);
> - }
> + pte_t *pte, *start_pte;
> + unsigned long long start_addr = addr;
> +
> + start_pte = pte = pte_offset_kernel(pmd, addr);
> + do {
> + if (!pte_none(*pte)) {
> + kvm_set_pte(pte, __pte(0));
> + put_page(virt_to_page(pte));
> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> + }
> + } while (pte++, addr += PAGE_SIZE, addr != end);
> +
> + if (kvm_pte_table_empty(start_pte))
> + clear_pmd_entry(kvm, pmd, start_addr);
I don't quite follow this clear_p[um]d_entry logic.
So this clear_pmd_entry will de-allocate the page containing the ptes
(referenced from the pmd entry)?
If so, what happens if not all the ptes in the page need to be unmapped?
The clear_p[um]d_entry functions appear to be split in two with one
codepath for huge entries (without any de-allocation) and the other
path for table entries that does have de-allocation. Would it be
better to perhaps split these functions in two with a more descriptive
name for the clear and de-allocate case?
> }
>
> -static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> - unsigned long long start, u64 size)
> +static void unmap_pmds(struct kvm *kvm, pud_t *pud,
> + unsigned long long addr, unsigned long long end)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> - pmd_t *pmd;
> - pte_t *pte;
> - unsigned long long addr = start, end = start + size;
> - u64 next;
> -
> - while (addr < end) {
> - pgd = pgdp + pgd_index(addr);
> - pud = pud_offset(pgd, addr);
> - pte = NULL;
> - if (pud_none(*pud)) {
> - addr = kvm_pud_addr_end(addr, end);
> - continue;
> - }
> + unsigned long long next, start_addr = addr;
> + pmd_t *pmd, *start_pmd;
>
> - if (pud_huge(*pud)) {
> - /*
> - * If we are dealing with a huge pud, just clear it and
> - * move on.
> - */
> - clear_pud_entry(kvm, pud, addr);
> - addr = kvm_pud_addr_end(addr, end);
> - continue;
> + start_pmd = pmd = pmd_offset(pud, addr);
> + do {
> + next = kvm_pmd_addr_end(addr, end);
> + if (!pmd_none(*pmd)) {
> + if (kvm_pmd_huge(*pmd))
> + clear_pmd_entry(kvm, pmd, addr);
> + else
> + unmap_ptes(kvm, pmd, addr, next);
> }
> + } while (pmd++, addr = next, addr != end);
>
> - pmd = pmd_offset(pud, addr);
> - if (pmd_none(*pmd)) {
> - addr = kvm_pmd_addr_end(addr, end);
> - continue;
> - }
> + if (kvm_pmd_table_empty(start_pmd))
> + clear_pud_entry(kvm, pud, start_addr);
> +}
>
> - if (!kvm_pmd_huge(*pmd)) {
> - pte = pte_offset_kernel(pmd, addr);
> - clear_pte_entry(kvm, pte, addr);
> - next = addr + PAGE_SIZE;
> - }
> +static void unmap_puds(struct kvm *kvm, pgd_t *pgd,
> + unsigned long long addr, unsigned long long end)
> +{
> + unsigned long long next, start_addr = addr;
> + pud_t *pud, *start_pud;
>
> - /*
> - * If the pmd entry is to be cleared, walk back up the ladder
> - */
> - if (kvm_pmd_huge(*pmd) || (pte && page_empty(pte))) {
> - clear_pmd_entry(kvm, pmd, addr);
> - next = kvm_pmd_addr_end(addr, end);
> - if (page_empty(pmd) && !page_empty(pud)) {
> + start_pud = pud = pud_offset(pgd, addr);
> + do {
> + next = kvm_pud_addr_end(addr, end);
> + if (!pud_none(*pud)) {
> + if (pud_huge(*pid)) {
> clear_pud_entry(kvm, pud, addr);
> - next = kvm_pud_addr_end(addr, end);
> + } else {
> + unmap_pmds(kvm, pud, addr, next);
> }
> }
> + } while (pud++, addr = next, addr != end);
>
> - addr = next;
> - }
> + if (kvm_pud_table_empty(start_pud))
> + clear_pgd_entry(kvm, pgd, start_addr);
> +}
> +
> +
> +static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> + unsigned long long start, u64 size)
> +{
> + pgd_t *pgd;
> + unsigned long long addr = start, end = start + size;
> + unsigned long long next;
> +
> + pgd = pgdp + pgd_index(addr);
> + do {
> + next = kvm_pgd_addr_end(addr, end);
> + unmap_puds(kvm, pgd, addr, next);
> + } while (pgd++, addr = next, addr != end);
> }
>
> static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 7d29847..8e138c7 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -125,6 +125,21 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> #define kvm_pud_addr_end(addr, end) pud_addr_end(addr, end)
> #define kvm_pmd_addr_end(addr, end) pmd_addr_end(addr, end)
>
> +static inline bool kvm_page_empty(void *ptr)
> +{
> + struct page *ptr_page = virt_to_page(ptr);
> + return page_count(ptr_page) == 1;
> +}
> +
> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> +#ifndef CONFIG_ARM64_64K_PAGES
> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> +#else
> +#define kvm_pmd_table_empty(pmdp) (0)
> +#endif
> +#define kvm_pud_table_empty(pudp) (0)
> +
> +
> struct kvm;
>
> #define kvm_flush_dcache_to_poc(a,l) __flush_dcache_area((a), (l))
> --
> 1.8.5.2
>
Cheers,
--
Steve
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-06-03 13:52 ` Steve Capper
@ 2014-06-04 13:30 ` Christoffer Dall
2014-06-04 13:37 ` Marc Zyngier
2014-06-04 13:59 ` Steve Capper
0 siblings, 2 replies; 10+ messages in thread
From: Christoffer Dall @ 2014-06-04 13:30 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Jun 03, 2014 at 02:52:58PM +0100, Steve Capper wrote:
> Hi Christoffer,
> I have some comments below:
>
> On 28 May 2014 15:22, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> > unmap_range() was utterly broken, to quote Marc, and broke in all sorts
> > of situations. It was also quite complicated to follow and didn't
> > follow the usual scheme of having a separate iterating function for each
> > level of page tables.
> >
> > Address this by refactoring the code and introduce a pgd_clear()
> > function.
> >
> > Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> > ---
> > Changes since v2:
> > - Don't define custom __unused but reuse __maybe_unused
> >
> > arch/arm/include/asm/kvm_mmu.h | 12 ++++
> > arch/arm/kvm/mmu.c | 122 ++++++++++++++++++++++-----------------
> > arch/arm64/include/asm/kvm_mmu.h | 15 +++++
> > 3 files changed, 95 insertions(+), 54 deletions(-)
> >
> > diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> > index 5c7aa3c..5cc0b0f 100644
> > --- a/arch/arm/include/asm/kvm_mmu.h
> > +++ b/arch/arm/include/asm/kvm_mmu.h
> > @@ -127,6 +127,18 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> > (__boundary - 1 < (end) - 1)? __boundary: (end); \
> > })
> >
> > +static inline bool kvm_page_empty(void *ptr)
> > +{
> > + struct page *ptr_page = virt_to_page(ptr);
> > + return page_count(ptr_page) == 1;
> > +}
> > +
> > +
> > +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> > +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> > +#define kvm_pud_table_empty(pudp) (0)
> > +
> > +
> > struct kvm;
> >
> > #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> > index 16f8049..6ee6e06 100644
> > --- a/arch/arm/kvm/mmu.c
> > +++ b/arch/arm/kvm/mmu.c
> > @@ -90,10 +90,13 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> > return p;
> > }
> >
> > -static bool page_empty(void *ptr)
> > +static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
> > {
> > - struct page *ptr_page = virt_to_page(ptr);
> > - return page_count(ptr_page) == 1;
> > + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
> > + pgd_clear(pgd);
> > + kvm_tlb_flush_vmid_ipa(kvm, addr);
> > + pud_free(NULL, pud_table);
> > + put_page(virt_to_page(pgd));
> > }
> >
> > static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> > @@ -124,70 +127,81 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
> > put_page(virt_to_page(pmd));
> > }
> >
> > -static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
> > +static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
> > + unsigned long long addr, unsigned long long end)
>
> We have a lot of unsigned long longs in this patch, should they not be
> phys_addr_t instead?
>
I guess they should, I *think* the confusion came from the fact that
unmap_range is also called on the hyp page table manipulation code,
which works on VAs and not PAs, and we wanted to avoid the confusion.
But I can't be sure.
That being said, I'm thinking that once we fix the whoel
SL0/TTBR0_X/T0SZ dynamic mess, then this function may no longer work for
both hyp page tables and Stage-2 page tables and then even this pseudo
relevant argument goes away.
I would like to see if Marc remembers something here, but otherwise we
could change all the unsigned long long's to phys_addr_t's.
> > {
> > - if (pte_present(*pte)) {
> > - kvm_set_pte(pte, __pte(0));
> > - put_page(virt_to_page(pte));
> > - kvm_tlb_flush_vmid_ipa(kvm, addr);
> > - }
> > + pte_t *pte, *start_pte;
> > + unsigned long long start_addr = addr;
> > +
> > + start_pte = pte = pte_offset_kernel(pmd, addr);
> > + do {
> > + if (!pte_none(*pte)) {
> > + kvm_set_pte(pte, __pte(0));
> > + put_page(virt_to_page(pte));
> > + kvm_tlb_flush_vmid_ipa(kvm, addr);
> > + }
> > + } while (pte++, addr += PAGE_SIZE, addr != end);
> > +
> > + if (kvm_pte_table_empty(start_pte))
> > + clear_pmd_entry(kvm, pmd, start_addr);
>
> I don't quite follow this clear_p[um]d_entry logic.
> So this clear_pmd_entry will de-allocate the page containing the ptes
> (referenced from the pmd entry)?
Yes.
> If so, what happens if not all the ptes in the page need to be unmapped?
Well, then pte_table_empty() will return false (because there are still
active pte's in the pte table) and we won't call the function.
The idea is that we ref-count each page table page with the number of
active entries in that page (in addition to the initial reference from
allocating the table). So a ref-count of 1 means that there are no
active entries (xxx_table_empty() returns true), a refcount of 513 means
there are 512 active entries.
Makes sense?
>
> The clear_p[um]d_entry functions appear to be split in two with one
> codepath for huge entries (without any de-allocation) and the other
> path for table entries that does have de-allocation. Would it be
> better to perhaps split these functions in two with a more descriptive
> name for the clear and de-allocate case?
yeah, that might make it less convoluted. I'll have a go at that (the
huge path can just be inlined into the unmap functions I believe).
>
> > }
> >
> > -static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> > - unsigned long long start, u64 size)
> > +static void unmap_pmds(struct kvm *kvm, pud_t *pud,
> > + unsigned long long addr, unsigned long long end)
> > {
> > - pgd_t *pgd;
> > - pud_t *pud;
> > - pmd_t *pmd;
> > - pte_t *pte;
> > - unsigned long long addr = start, end = start + size;
> > - u64 next;
> > -
> > - while (addr < end) {
> > - pgd = pgdp + pgd_index(addr);
> > - pud = pud_offset(pgd, addr);
> > - pte = NULL;
> > - if (pud_none(*pud)) {
> > - addr = kvm_pud_addr_end(addr, end);
> > - continue;
> > - }
> > + unsigned long long next, start_addr = addr;
> > + pmd_t *pmd, *start_pmd;
> >
> > - if (pud_huge(*pud)) {
> > - /*
> > - * If we are dealing with a huge pud, just clear it and
> > - * move on.
> > - */
> > - clear_pud_entry(kvm, pud, addr);
> > - addr = kvm_pud_addr_end(addr, end);
> > - continue;
> > + start_pmd = pmd = pmd_offset(pud, addr);
> > + do {
> > + next = kvm_pmd_addr_end(addr, end);
> > + if (!pmd_none(*pmd)) {
> > + if (kvm_pmd_huge(*pmd))
> > + clear_pmd_entry(kvm, pmd, addr);
> > + else
> > + unmap_ptes(kvm, pmd, addr, next);
> > }
> > + } while (pmd++, addr = next, addr != end);
> >
> > - pmd = pmd_offset(pud, addr);
> > - if (pmd_none(*pmd)) {
> > - addr = kvm_pmd_addr_end(addr, end);
> > - continue;
> > - }
> > + if (kvm_pmd_table_empty(start_pmd))
> > + clear_pud_entry(kvm, pud, start_addr);
> > +}
> >
> > - if (!kvm_pmd_huge(*pmd)) {
> > - pte = pte_offset_kernel(pmd, addr);
> > - clear_pte_entry(kvm, pte, addr);
> > - next = addr + PAGE_SIZE;
> > - }
> > +static void unmap_puds(struct kvm *kvm, pgd_t *pgd,
> > + unsigned long long addr, unsigned long long end)
> > +{
> > + unsigned long long next, start_addr = addr;
> > + pud_t *pud, *start_pud;
> >
> > - /*
> > - * If the pmd entry is to be cleared, walk back up the ladder
> > - */
> > - if (kvm_pmd_huge(*pmd) || (pte && page_empty(pte))) {
> > - clear_pmd_entry(kvm, pmd, addr);
> > - next = kvm_pmd_addr_end(addr, end);
> > - if (page_empty(pmd) && !page_empty(pud)) {
> > + start_pud = pud = pud_offset(pgd, addr);
> > + do {
> > + next = kvm_pud_addr_end(addr, end);
> > + if (!pud_none(*pud)) {
> > + if (pud_huge(*pid)) {
> > clear_pud_entry(kvm, pud, addr);
> > - next = kvm_pud_addr_end(addr, end);
> > + } else {
> > + unmap_pmds(kvm, pud, addr, next);
> > }
> > }
> > + } while (pud++, addr = next, addr != end);
> >
> > - addr = next;
> > - }
> > + if (kvm_pud_table_empty(start_pud))
> > + clear_pgd_entry(kvm, pgd, start_addr);
> > +}
> > +
> > +
> > +static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
> > + unsigned long long start, u64 size)
> > +{
> > + pgd_t *pgd;
> > + unsigned long long addr = start, end = start + size;
> > + unsigned long long next;
> > +
> > + pgd = pgdp + pgd_index(addr);
> > + do {
> > + next = kvm_pgd_addr_end(addr, end);
> > + unmap_puds(kvm, pgd, addr, next);
> > + } while (pgd++, addr = next, addr != end);
> > }
> >
> > static void stage2_flush_ptes(struct kvm *kvm, pmd_t *pmd,
> > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> > index 7d29847..8e138c7 100644
> > --- a/arch/arm64/include/asm/kvm_mmu.h
> > +++ b/arch/arm64/include/asm/kvm_mmu.h
> > @@ -125,6 +125,21 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> > #define kvm_pud_addr_end(addr, end) pud_addr_end(addr, end)
> > #define kvm_pmd_addr_end(addr, end) pmd_addr_end(addr, end)
> >
> > +static inline bool kvm_page_empty(void *ptr)
> > +{
> > + struct page *ptr_page = virt_to_page(ptr);
> > + return page_count(ptr_page) == 1;
> > +}
> > +
> > +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> > +#ifndef CONFIG_ARM64_64K_PAGES
> > +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> > +#else
> > +#define kvm_pmd_table_empty(pmdp) (0)
> > +#endif
> > +#define kvm_pud_table_empty(pudp) (0)
> > +
> > +
> > struct kvm;
> >
> > #define kvm_flush_dcache_to_poc(a,l) __flush_dcache_area((a), (l))
> > --
> > 1.8.5.2
> >
>
> Cheers,
Thanks for looking at the code!
-Christoffer
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-06-04 13:30 ` Christoffer Dall
@ 2014-06-04 13:37 ` Marc Zyngier
2014-06-04 13:54 ` Christoffer Dall
2014-06-04 13:59 ` Steve Capper
1 sibling, 1 reply; 10+ messages in thread
From: Marc Zyngier @ 2014-06-04 13:37 UTC (permalink / raw)
To: linux-arm-kernel
On 04/06/14 14:30, Christoffer Dall wrote:
> On Tue, Jun 03, 2014 at 02:52:58PM +0100, Steve Capper wrote:
>> Hi Christoffer,
>> I have some comments below:
>>
>> On 28 May 2014 15:22, Christoffer Dall <christoffer.dall@linaro.org> wrote:
>>> unmap_range() was utterly broken, to quote Marc, and broke in all sorts
>>> of situations. It was also quite complicated to follow and didn't
>>> follow the usual scheme of having a separate iterating function for each
>>> level of page tables.
>>>
>>> Address this by refactoring the code and introduce a pgd_clear()
>>> function.
>>>
>>> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
>>> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
>>> ---
>>> Changes since v2:
>>> - Don't define custom __unused but reuse __maybe_unused
>>>
>>> arch/arm/include/asm/kvm_mmu.h | 12 ++++
>>> arch/arm/kvm/mmu.c | 122 ++++++++++++++++++++++-----------------
>>> arch/arm64/include/asm/kvm_mmu.h | 15 +++++
>>> 3 files changed, 95 insertions(+), 54 deletions(-)
>>>
>>> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
>>> index 5c7aa3c..5cc0b0f 100644
>>> --- a/arch/arm/include/asm/kvm_mmu.h
>>> +++ b/arch/arm/include/asm/kvm_mmu.h
>>> @@ -127,6 +127,18 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
>>> (__boundary - 1 < (end) - 1)? __boundary: (end); \
>>> })
>>>
>>> +static inline bool kvm_page_empty(void *ptr)
>>> +{
>>> + struct page *ptr_page = virt_to_page(ptr);
>>> + return page_count(ptr_page) == 1;
>>> +}
>>> +
>>> +
>>> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
>>> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
>>> +#define kvm_pud_table_empty(pudp) (0)
>>> +
>>> +
>>> struct kvm;
>>>
>>> #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
>>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
>>> index 16f8049..6ee6e06 100644
>>> --- a/arch/arm/kvm/mmu.c
>>> +++ b/arch/arm/kvm/mmu.c
>>> @@ -90,10 +90,13 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
>>> return p;
>>> }
>>>
>>> -static bool page_empty(void *ptr)
>>> +static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
>>> {
>>> - struct page *ptr_page = virt_to_page(ptr);
>>> - return page_count(ptr_page) == 1;
>>> + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
>>> + pgd_clear(pgd);
>>> + kvm_tlb_flush_vmid_ipa(kvm, addr);
>>> + pud_free(NULL, pud_table);
>>> + put_page(virt_to_page(pgd));
>>> }
>>>
>>> static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
>>> @@ -124,70 +127,81 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
>>> put_page(virt_to_page(pmd));
>>> }
>>>
>>> -static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
>>> +static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
>>> + unsigned long long addr, unsigned long long end)
>>
>> We have a lot of unsigned long longs in this patch, should they not be
>> phys_addr_t instead?
>>
>
> I guess they should, I *think* the confusion came from the fact that
> unmap_range is also called on the hyp page table manipulation code,
> which works on VAs and not PAs, and we wanted to avoid the confusion.
> But I can't be sure.
>
> That being said, I'm thinking that once we fix the whoel
> SL0/TTBR0_X/T0SZ dynamic mess, then this function may no longer work for
> both hyp page tables and Stage-2 page tables and then even this pseudo
> relevant argument goes away.
>
> I would like to see if Marc remembers something here, but otherwise we
> could change all the unsigned long long's to phys_addr_t's.
I don't think that'd be a problem, as long as we have a nice comment
about that.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-06-04 13:37 ` Marc Zyngier
@ 2014-06-04 13:54 ` Christoffer Dall
0 siblings, 0 replies; 10+ messages in thread
From: Christoffer Dall @ 2014-06-04 13:54 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Jun 04, 2014 at 02:37:42PM +0100, Marc Zyngier wrote:
> On 04/06/14 14:30, Christoffer Dall wrote:
> > On Tue, Jun 03, 2014 at 02:52:58PM +0100, Steve Capper wrote:
> >> Hi Christoffer,
> >> I have some comments below:
> >>
> >> On 28 May 2014 15:22, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> >>> unmap_range() was utterly broken, to quote Marc, and broke in all sorts
> >>> of situations. It was also quite complicated to follow and didn't
> >>> follow the usual scheme of having a separate iterating function for each
> >>> level of page tables.
> >>>
> >>> Address this by refactoring the code and introduce a pgd_clear()
> >>> function.
> >>>
> >>> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> >>> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> >>> ---
> >>> Changes since v2:
> >>> - Don't define custom __unused but reuse __maybe_unused
> >>>
> >>> arch/arm/include/asm/kvm_mmu.h | 12 ++++
> >>> arch/arm/kvm/mmu.c | 122 ++++++++++++++++++++++-----------------
> >>> arch/arm64/include/asm/kvm_mmu.h | 15 +++++
> >>> 3 files changed, 95 insertions(+), 54 deletions(-)
> >>>
> >>> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> >>> index 5c7aa3c..5cc0b0f 100644
> >>> --- a/arch/arm/include/asm/kvm_mmu.h
> >>> +++ b/arch/arm/include/asm/kvm_mmu.h
> >>> @@ -127,6 +127,18 @@ static inline void kvm_set_s2pmd_writable(pmd_t *pmd)
> >>> (__boundary - 1 < (end) - 1)? __boundary: (end); \
> >>> })
> >>>
> >>> +static inline bool kvm_page_empty(void *ptr)
> >>> +{
> >>> + struct page *ptr_page = virt_to_page(ptr);
> >>> + return page_count(ptr_page) == 1;
> >>> +}
> >>> +
> >>> +
> >>> +#define kvm_pte_table_empty(ptep) kvm_page_empty(ptep)
> >>> +#define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
> >>> +#define kvm_pud_table_empty(pudp) (0)
> >>> +
> >>> +
> >>> struct kvm;
> >>>
> >>> #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> >>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> >>> index 16f8049..6ee6e06 100644
> >>> --- a/arch/arm/kvm/mmu.c
> >>> +++ b/arch/arm/kvm/mmu.c
> >>> @@ -90,10 +90,13 @@ static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> >>> return p;
> >>> }
> >>>
> >>> -static bool page_empty(void *ptr)
> >>> +static void clear_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr)
> >>> {
> >>> - struct page *ptr_page = virt_to_page(ptr);
> >>> - return page_count(ptr_page) == 1;
> >>> + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0);
> >>> + pgd_clear(pgd);
> >>> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> >>> + pud_free(NULL, pud_table);
> >>> + put_page(virt_to_page(pgd));
> >>> }
> >>>
> >>> static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
> >>> @@ -124,70 +127,81 @@ static void clear_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr)
> >>> put_page(virt_to_page(pmd));
> >>> }
> >>>
> >>> -static void clear_pte_entry(struct kvm *kvm, pte_t *pte, phys_addr_t addr)
> >>> +static void unmap_ptes(struct kvm *kvm, pmd_t *pmd,
> >>> + unsigned long long addr, unsigned long long end)
> >>
> >> We have a lot of unsigned long longs in this patch, should they not be
> >> phys_addr_t instead?
> >>
> >
> > I guess they should, I *think* the confusion came from the fact that
> > unmap_range is also called on the hyp page table manipulation code,
> > which works on VAs and not PAs, and we wanted to avoid the confusion.
> > But I can't be sure.
> >
> > That being said, I'm thinking that once we fix the whoel
> > SL0/TTBR0_X/T0SZ dynamic mess, then this function may no longer work for
> > both hyp page tables and Stage-2 page tables and then even this pseudo
> > relevant argument goes away.
> >
> > I would like to see if Marc remembers something here, but otherwise we
> > could change all the unsigned long long's to phys_addr_t's.
>
> I don't think that'd be a problem, as long as we have a nice comment
> about that.
>
ok, I'll fix it in the next revision.
-Christoffer
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v2] arm/arm64: KVM: Fix and refactor unmap_range
2014-06-04 13:30 ` Christoffer Dall
2014-06-04 13:37 ` Marc Zyngier
@ 2014-06-04 13:59 ` Steve Capper
1 sibling, 0 replies; 10+ messages in thread
From: Steve Capper @ 2014-06-04 13:59 UTC (permalink / raw)
To: linux-arm-kernel
On 4 June 2014 14:30, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> On Tue, Jun 03, 2014 at 02:52:58PM +0100, Steve Capper wrote:
[ ... ]
>>
>> I don't quite follow this clear_p[um]d_entry logic.
>> So this clear_pmd_entry will de-allocate the page containing the ptes
>> (referenced from the pmd entry)?
>
> Yes.
>
>> If so, what happens if not all the ptes in the page need to be unmapped?
>
> Well, then pte_table_empty() will return false (because there are still
> active pte's in the pte table) and we won't call the function.
>
> The idea is that we ref-count each page table page with the number of
> active entries in that page (in addition to the initial reference from
> allocating the table). So a ref-count of 1 means that there are no
> active entries (xxx_table_empty() returns true), a refcount of 513 means
> there are 512 active entries.
>
> Makes sense?
Thanks Christoffer,
Yes that makes perfect sense.
Cheers,
--
Steve
^ permalink raw reply [flat|nested] 10+ messages in thread