lkml.org 
[lkml]   [2021]   [Jul]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [RFC PATCH v2 28/69] KVM: Add per-VM flag to mark read-only memory as unsupported
    From
    Date
    On 03/07/21 00:04, isaku.yamahata@intel.com wrote:
    > From: Isaku Yamahata <isaku.yamahata@intel.com>
    >
    > Add a flag for TDX to flag RO memory as unsupported and propagate it to
    > KVM_MEM_READONLY to allow reporting RO memory as unsupported on a per-VM
    > basis. TDX1 doesn't expose permission bits to the VMM in the SEPT
    > tables, i.e. doesn't support read-only private memory.
    >
    > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    > Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
    > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    > ---
    > arch/x86/kvm/x86.c | 4 +++-
    > include/linux/kvm_host.h | 4 ++++
    > virt/kvm/kvm_main.c | 8 +++++---
    > 3 files changed, 12 insertions(+), 4 deletions(-)
    >
    > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    > index cd9407982366..87212d7563ae 100644
    > --- a/arch/x86/kvm/x86.c
    > +++ b/arch/x86/kvm/x86.c
    > @@ -3897,7 +3897,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
    > case KVM_CAP_ASYNC_PF_INT:
    > case KVM_CAP_GET_TSC_KHZ:
    > case KVM_CAP_KVMCLOCK_CTRL:
    > - case KVM_CAP_READONLY_MEM:
    > case KVM_CAP_HYPERV_TIME:
    > case KVM_CAP_IOAPIC_POLARITY_IGNORED:
    > case KVM_CAP_TSC_DEADLINE_TIMER:
    > @@ -4009,6 +4008,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
    > if (static_call(kvm_x86_is_vm_type_supported)(KVM_X86_TDX_VM))
    > r |= BIT(KVM_X86_TDX_VM);
    > break;
    > + case KVM_CAP_READONLY_MEM:
    > + r = kvm && kvm->readonly_mem_unsupported ? 0 : 1;
    > + break;
    > default:
    > break;
    > }
    > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    > index ddd4d0f68cdf..7ee7104b4b59 100644
    > --- a/include/linux/kvm_host.h
    > +++ b/include/linux/kvm_host.h
    > @@ -597,6 +597,10 @@ struct kvm {
    > unsigned int max_halt_poll_ns;
    > u32 dirty_ring_size;
    >
    > +#ifdef __KVM_HAVE_READONLY_MEM
    > + bool readonly_mem_unsupported;
    > +#endif
    > +
    > bool vm_bugged;
    > };
    >
    > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    > index 52d40ea75749..63d0c2833913 100644
    > --- a/virt/kvm/kvm_main.c
    > +++ b/virt/kvm/kvm_main.c
    > @@ -1258,12 +1258,14 @@ static void update_memslots(struct kvm_memslots *slots,
    > }
    > }
    >
    > -static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
    > +static int check_memory_region_flags(struct kvm *kvm,
    > + const struct kvm_userspace_memory_region *mem)
    > {
    > u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
    >
    > #ifdef __KVM_HAVE_READONLY_MEM
    > - valid_flags |= KVM_MEM_READONLY;
    > + if (!kvm->readonly_mem_unsupported)
    > + valid_flags |= KVM_MEM_READONLY;
    > #endif
    >
    > if (mem->flags & ~valid_flags)
    > @@ -1436,7 +1438,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
    > int as_id, id;
    > int r;
    >
    > - r = check_memory_region_flags(mem);
    > + r = check_memory_region_flags(kvm, mem);
    > if (r)
    > return r;
    >
    >

    For all these flags, which of these limitations will be common to SEV-ES
    and SEV-SNP (ExtINT injection, MCE injection, changing TSC, read-only
    memory, dirty logging)? Would it make sense to use vm_type instead of
    all of them? I guess this also guides the choice of whether to use a
    single vm-type for TDX and SEV-SNP or two. Probably two is better, and
    there can be static inline bool functions to derive the support flags
    from the vm-type.

    Paolo

    \
     
     \ /
      Last update: 2021-07-06 16:34    [W:5.071 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site