On 06.08.2013, at 06:19, Paul Mackerras wrote:
> Currently, PR KVM uses 4k pages for the host-side mappings of guest
> memory, regardless of the host page size. When the host page size is
> 64kB, we might as well use 64k host page mappings for guest mappings
> of 64kB and larger pages and for guest real-mode mappings. However,
> the magic page has to remain a 4k page.
>
> To implement this, we first add another flag bit to the guest VSID
> values we use, to indicate that this segment is one where host pages
> should be mapped using 64k pages. For segments with this bit set
> we set the bits in the shadow SLB entry to indicate a 64k base page
> size. When faulting in host HPTEs for this segment, we make them
> 64k HPTEs instead of 4k. We record the pagesize in struct hpte_cache
> for use when invalidating the HPTE.
>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
> ---
> arch/powerpc/include/asm/kvm_book3s.h | 6 ++++--
> arch/powerpc/kvm/book3s_32_mmu.c | 1 +
> arch/powerpc/kvm/book3s_64_mmu.c | 35 ++++++++++++++++++++++++++++++-----
> arch/powerpc/kvm/book3s_64_mmu_host.c | 27 +++++++++++++++++++++------
> arch/powerpc/kvm/book3s_pr.c | 1 +
> 5 files changed, 57 insertions(+), 13 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> index 175f876..322b539 100644
> --- a/arch/powerpc/include/asm/kvm_book3s.h
> +++ b/arch/powerpc/include/asm/kvm_book3s.h
> @@ -66,6 +66,7 @@ struct hpte_cache {
> u64 pfn;
> ulong slot;
> struct kvmppc_pte pte;
> + int pagesize;
> };
>
> struct kvmppc_vcpu_book3s {
> @@ -113,8 +114,9 @@ struct kvmppc_vcpu_book3s {
> #define CONTEXT_GUEST 1
> #define CONTEXT_GUEST_END 2
>
> -#define VSID_REAL 0x0fffffffffc00000ULL
> -#define VSID_BAT 0x0fffffffffb00000ULL
> +#define VSID_REAL 0x07ffffffffc00000ULL
> +#define VSID_BAT 0x07ffffffffb00000ULL
> +#define VSID_64K 0x0800000000000000ULL
> #define VSID_1T 0x1000000000000000ULL
> #define VSID_REAL_DR 0x2000000000000000ULL
> #define VSID_REAL_IR 0x4000000000000000ULL
> diff --git a/arch/powerpc/kvm/book3s_32_mmu.c b/arch/powerpc/kvm/book3s_32_mmu.c
> index c8cefdd..af04553 100644
> --- a/arch/powerpc/kvm/book3s_32_mmu.c
> +++ b/arch/powerpc/kvm/book3s_32_mmu.c
> @@ -308,6 +308,7 @@ static int kvmppc_mmu_book3s_32_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
> ulong mp_ea = vcpu->arch.magic_page_ea;
>
> pte->eaddr = eaddr;
> + pte->page_size = MMU_PAGE_4K;
>
> /* Magic page override */
> if (unlikely(mp_ea) &&
> diff --git a/arch/powerpc/kvm/book3s_64_mmu.c b/arch/powerpc/kvm/book3s_64_mmu.c
> index d5fa26c..658ccd7 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu.c
> @@ -542,6 +542,16 @@ static void kvmppc_mmu_book3s_64_tlbie(struct kvm_vcpu *vcpu, ulong va,
> kvmppc_mmu_pte_vflush(vcpu, va >> 12, mask);
> }
>
> +#ifdef CONFIG_PPC_64K_PAGES
> +static int segment_contains_magic_page(struct kvm_vcpu *vcpu, ulong esid)
> +{
> + ulong mp_ea = vcpu->arch.magic_page_ea;
> +
> + return mp_ea && !(vcpu->arch.shared->msr & MSR_PR) &&
> + (mp_ea >> SID_SHIFT) == esid;
> +}
> +#endif
> +
> static int kvmppc_mmu_book3s_64_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
> u64 *vsid)
> {
> @@ -549,11 +559,13 @@ static int kvmppc_mmu_book3s_64_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
> struct kvmppc_slb *slb;
> u64 gvsid = esid;
> ulong mp_ea = vcpu->arch.magic_page_ea;
> + int pagesize = MMU_PAGE_64K;
>
> if (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
> slb = kvmppc_mmu_book3s_64_find_slbe(vcpu, ea);
> if (slb) {
> gvsid = slb->vsid;
> + pagesize = slb->base_page_size;
> if (slb->tb) {
> gvsid <<= SID_SHIFT_1T - SID_SHIFT;
> gvsid |= esid & ((1ul << (SID_SHIFT_1T - SID_SHIFT)) - 1);
> @@ -564,28 +576,41 @@ static int kvmppc_mmu_book3s_64_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
>
> switch (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
> case 0:
> - *vsid = VSID_REAL | esid;
> + gvsid = VSID_REAL | esid;
> break;
> case MSR_IR:
> - *vsid = VSID_REAL_IR | gvsid;
> + gvsid |= VSID_REAL_IR;
> break;
> case MSR_DR:
> - *vsid = VSID_REAL_DR | gvsid;
> + gvsid |= VSID_REAL_DR;
> break;
> case MSR_DR|MSR_IR:
> if (!slb)
> goto no_slb;
>
> - *vsid = gvsid;
> break;
> default:
> BUG();
> break;
> }
>
> +#ifdef CONFIG_PPC_64K_PAGES
> + /*
> + * Mark this as a 64k segment if the host is using
> + * 64k pages, the host MMU supports 64k pages and
> + * the guest segment page size is >= 64k,
> + * but not if this segment contains the magic page.
What's the problem with the magic page? As long as we map the magic page as a host 64k page and access only the upper 4k (which we handle today already) we should be set, no?
Alex
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