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SubjectRe: [PATCH v1 14/16] kvm: arm64: Switch to per VM IPA
On Thu, Feb 08, 2018 at 05:22:29PM +0000, Suzuki K Poulose wrote:
> On 08/02/18 11:00, Christoffer Dall wrote:
> >On Tue, Jan 09, 2018 at 07:04:09PM +0000, Suzuki K Poulose wrote:
> >>Now that we can manage the stage2 page table per VM, switch the
> >>configuration details to per VM instance. We keep track of the
> >>IPA bits, number of page table levels and the VTCR bits (which
> >>depends on the IPA and the number of levels).
> >>
> >>Cc: Marc Zyngier <marc.zyngier@arm.com>
> >>Cc: Christoffer Dall <cdall@linaro.org>
> >>Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> >>---
> >> arch/arm/include/asm/kvm_mmu.h | 1 +
> >> arch/arm64/include/asm/kvm_host.h | 12 ++++++++++++
> >> arch/arm64/include/asm/kvm_mmu.h | 22 ++++++++++++++++++++--
> >> arch/arm64/include/asm/stage2_pgtable.h | 1 -
> >> arch/arm64/kvm/hyp/switch.c | 3 +--
> >> virt/kvm/arm/arm.c | 2 +-
> >> 6 files changed, 35 insertions(+), 6 deletions(-)
> >>
> >>diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> >>index 440c80589453..dd592fe45660 100644
> >>--- a/arch/arm/include/asm/kvm_mmu.h
> >>+++ b/arch/arm/include/asm/kvm_mmu.h
> >>@@ -48,6 +48,7 @@
> >> #define kvm_vttbr_baddr_mask(kvm) VTTBR_BADDR_MASK
> >> #define stage2_pgd_size(kvm) (PTRS_PER_S2_PGD * sizeof(pgd_t))
> >>+#define kvm_init_stage2_config(kvm) do { } while (0)
> >> int create_hyp_mappings(void *from, void *to, pgprot_t prot);
> >> int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
> >> void free_hyp_pgds(void);
> >>diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> >>index 9a9ddeb33c84..1e66e5ab3dde 100644
> >>--- a/arch/arm64/include/asm/kvm_host.h
> >>+++ b/arch/arm64/include/asm/kvm_host.h
> >>@@ -64,6 +64,18 @@ struct kvm_arch {
> >> /* VTTBR value associated with above pgd and vmid */
> >> u64 vttbr;
> >>+ /* Private bits of VTCR_EL2 for this VM */
> >>+ u64 vtcr_private;
> >
> >As to my comments in the previous patch, why isn't this simply u64 vtcr;
>
> nit: I haven't received your response to the previous patch.

It got stuck in my drafts folder somehow, hopefully you received it now.

>
> We could. I thought this gives a bit more clarity on what changes per-VM.
>

Since there's a performance issue involved, I think it's cleaner to just
calculate the vtcr once per VM and store it.

Thanks,
-Christoffer
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