Messages in this thread | | | Subject | Re: [PATCH v6 08/14] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall | From | Krish Sadhukhan <> | Date | Mon, 6 Apr 2020 15:27:08 -0700 |
| |
On 4/2/20 7:58 PM, Ashish Kalra wrote: > On Fri, Apr 03, 2020 at 01:57:48AM +0000, Ashish Kalra wrote: >> On Thu, Apr 02, 2020 at 06:31:54PM -0700, Krish Sadhukhan wrote: >>> On 3/29/20 11:22 PM, Ashish Kalra wrote: >>>> From: Brijesh Singh <Brijesh.Singh@amd.com> >>>> >>>> This hypercall is used by the SEV guest to notify a change in the page >>>> encryption status to the hypervisor. The hypercall should be invoked >>>> only when the encryption attribute is changed from encrypted -> decrypted >>>> and vice versa. By default all guest pages are considered encrypted. >>>> >>>> Cc: Thomas Gleixner <tglx@linutronix.de> >>>> Cc: Ingo Molnar <mingo@redhat.com> >>>> Cc: "H. Peter Anvin" <hpa@zytor.com> >>>> Cc: Paolo Bonzini <pbonzini@redhat.com> >>>> Cc: "Radim Krčmář" <rkrcmar@redhat.com> >>>> Cc: Joerg Roedel <joro@8bytes.org> >>>> Cc: Borislav Petkov <bp@suse.de> >>>> Cc: Tom Lendacky <thomas.lendacky@amd.com> >>>> Cc: x86@kernel.org >>>> Cc: kvm@vger.kernel.org >>>> Cc: linux-kernel@vger.kernel.org >>>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> >>>> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> >>>> --- >>>> Documentation/virt/kvm/hypercalls.rst | 15 +++++ >>>> arch/x86/include/asm/kvm_host.h | 2 + >>>> arch/x86/kvm/svm.c | 95 +++++++++++++++++++++++++++ >>>> arch/x86/kvm/vmx/vmx.c | 1 + >>>> arch/x86/kvm/x86.c | 6 ++ >>>> include/uapi/linux/kvm_para.h | 1 + >>>> 6 files changed, 120 insertions(+) >>>> >>>> diff --git a/Documentation/virt/kvm/hypercalls.rst b/Documentation/virt/kvm/hypercalls.rst >>>> index dbaf207e560d..ff5287e68e81 100644 >>>> --- a/Documentation/virt/kvm/hypercalls.rst >>>> +++ b/Documentation/virt/kvm/hypercalls.rst >>>> @@ -169,3 +169,18 @@ a0: destination APIC ID >>>> :Usage example: When sending a call-function IPI-many to vCPUs, yield if >>>> any of the IPI target vCPUs was preempted. >>>> + >>>> + >>>> +8. KVM_HC_PAGE_ENC_STATUS >>>> +------------------------- >>>> +:Architecture: x86 >>>> +:Status: active >>>> +:Purpose: Notify the encryption status changes in guest page table (SEV guest) >>>> + >>>> +a0: the guest physical address of the start page >>>> +a1: the number of pages >>>> +a2: encryption attribute >>>> + >>>> + Where: >>>> + * 1: Encryption attribute is set >>>> + * 0: Encryption attribute is cleared >>>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >>>> index 98959e8cd448..90718fa3db47 100644 >>>> --- a/arch/x86/include/asm/kvm_host.h >>>> +++ b/arch/x86/include/asm/kvm_host.h >>>> @@ -1267,6 +1267,8 @@ struct kvm_x86_ops { >>>> bool (*apic_init_signal_blocked)(struct kvm_vcpu *vcpu); >>>> int (*enable_direct_tlbflush)(struct kvm_vcpu *vcpu); >>>> + int (*page_enc_status_hc)(struct kvm *kvm, unsigned long gpa, >>>> + unsigned long sz, unsigned long mode); >>>> }; >>>> struct kvm_arch_async_pf { >>>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c >>>> index 7c2721e18b06..1d8beaf1bceb 100644 >>>> --- a/arch/x86/kvm/svm.c >>>> +++ b/arch/x86/kvm/svm.c >>>> @@ -136,6 +136,8 @@ struct kvm_sev_info { >>>> int fd; /* SEV device fd */ >>>> unsigned long pages_locked; /* Number of pages locked */ >>>> struct list_head regions_list; /* List of registered regions */ >>>> + unsigned long *page_enc_bmap; >>>> + unsigned long page_enc_bmap_size; >>>> }; >>>> struct kvm_svm { >>>> @@ -1991,6 +1993,9 @@ static void sev_vm_destroy(struct kvm *kvm) >>>> sev_unbind_asid(kvm, sev->handle); >>>> sev_asid_free(sev->asid); >>>> + >>>> + kvfree(sev->page_enc_bmap); >>>> + sev->page_enc_bmap = NULL; >>>> } >>>> static void avic_vm_destroy(struct kvm *kvm) >>>> @@ -7593,6 +7598,94 @@ static int sev_receive_finish(struct kvm *kvm, struct kvm_sev_cmd *argp) >>>> return ret; >>>> } >>>> +static int sev_resize_page_enc_bitmap(struct kvm *kvm, unsigned long new_size) >>>> +{ >>>> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >>>> + unsigned long *map; >>>> + unsigned long sz; >>>> + >>>> + if (sev->page_enc_bmap_size >= new_size) >>>> + return 0; >>>> + >>>> + sz = ALIGN(new_size, BITS_PER_LONG) / 8; >>>> + >>>> + map = vmalloc(sz); >>> >>> Just wondering why we can't directly modify sev->page_enc_bmap. >>> >> Because the page_enc_bitmap needs to be re-sized here, it needs to be >> expanded here.
OK.
> I don't believe there is anything is like a realloc() kind of equivalent > for the kmalloc() interfaces. > > Thanks, > Ashish > >>>> + if (!map) { >>>> + pr_err_once("Failed to allocate encrypted bitmap size %lx\n", >>>> + sz); >>>> + return -ENOMEM; >>>> + } >>>> + >>>> + /* mark the page encrypted (by default) */ >>>> + memset(map, 0xff, sz); >>>> + >>>> + bitmap_copy(map, sev->page_enc_bmap, sev->page_enc_bmap_size); >>>> + kvfree(sev->page_enc_bmap); >>>> + >>>> + sev->page_enc_bmap = map; >>>> + sev->page_enc_bmap_size = new_size; >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +static int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa, >>>> + unsigned long npages, unsigned long enc) >>>> +{ >>>> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >>>> + kvm_pfn_t pfn_start, pfn_end; >>>> + gfn_t gfn_start, gfn_end; >>>> + int ret; >>>> + >>>> + if (!sev_guest(kvm)) >>>> + return -EINVAL; >>>> + >>>> + if (!npages) >>>> + return 0; >>>> + >>>> + gfn_start = gpa_to_gfn(gpa); >>>> + gfn_end = gfn_start + npages; >>>> + >>>> + /* out of bound access error check */ >>>> + if (gfn_end <= gfn_start) >>>> + return -EINVAL; >>>> + >>>> + /* lets make sure that gpa exist in our memslot */ >>>> + pfn_start = gfn_to_pfn(kvm, gfn_start); >>>> + pfn_end = gfn_to_pfn(kvm, gfn_end); >>>> + >>>> + if (is_error_noslot_pfn(pfn_start) && !is_noslot_pfn(pfn_start)) { >>>> + /* >>>> + * Allow guest MMIO range(s) to be added >>>> + * to the page encryption bitmap. >>>> + */ >>>> + return -EINVAL; >>>> + } >>>> + >>>> + if (is_error_noslot_pfn(pfn_end) && !is_noslot_pfn(pfn_end)) { >>>> + /* >>>> + * Allow guest MMIO range(s) to be added >>>> + * to the page encryption bitmap. >>>> + */ >>>> + return -EINVAL; >>>> + } >>> >>> It seems is_error_noslot_pfn() covers both cases - i) gfn slot is absent, >>> ii) failure to translate to pfn. So do we still need is_noslot_pfn() ? >>> >> We do need to check for !is_noslot_pfn(..) additionally as the MMIO ranges will not >> be having a slot allocated.
The comments above is_error_noslot_pfn() seem to indicate that it covers both cases, "not in slot" and "failure to translate"...
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
>> >> Thanks, >> Ashish >> >>>> + >>>> + mutex_lock(&kvm->lock); >>>> + ret = sev_resize_page_enc_bitmap(kvm, gfn_end); >>>> + if (ret) >>>> + goto unlock; >>>> + >>>> + if (enc) >>>> + __bitmap_set(sev->page_enc_bmap, gfn_start, >>>> + gfn_end - gfn_start); >>>> + else >>>> + __bitmap_clear(sev->page_enc_bmap, gfn_start, >>>> + gfn_end - gfn_start); >>>> + >>>> +unlock: >>>> + mutex_unlock(&kvm->lock); >>>> + return ret; >>>> +} >>>> + >>>> static int svm_mem_enc_op(struct kvm *kvm, void __user *argp) >>>> { >>>> struct kvm_sev_cmd sev_cmd; >>>> @@ -7995,6 +8088,8 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { >>>> .need_emulation_on_page_fault = svm_need_emulation_on_page_fault, >>>> .apic_init_signal_blocked = svm_apic_init_signal_blocked, >>>> + >>>> + .page_enc_status_hc = svm_page_enc_status_hc, >>> >>> Why not place it where other encryption ops are located ? >>> >>> ... >>> >>> .mem_enc_unreg_region >>> >>> + .page_enc_status_hc = svm_page_enc_status_hc >>> >>>> }; >>>> static int __init svm_init(void) >>>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c >>>> index 079d9fbf278e..f68e76ee7f9c 100644 >>>> --- a/arch/x86/kvm/vmx/vmx.c >>>> +++ b/arch/x86/kvm/vmx/vmx.c >>>> @@ -8001,6 +8001,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { >>>> .nested_get_evmcs_version = NULL, >>>> .need_emulation_on_page_fault = vmx_need_emulation_on_page_fault, >>>> .apic_init_signal_blocked = vmx_apic_init_signal_blocked, >>>> + .page_enc_status_hc = NULL, >>>> }; >>>> static void vmx_cleanup_l1d_flush(void) >>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >>>> index cf95c36cb4f4..68428eef2dde 100644 >>>> --- a/arch/x86/kvm/x86.c >>>> +++ b/arch/x86/kvm/x86.c >>>> @@ -7564,6 +7564,12 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) >>>> kvm_sched_yield(vcpu->kvm, a0); >>>> ret = 0; >>>> break; >>>> + case KVM_HC_PAGE_ENC_STATUS: >>>> + ret = -KVM_ENOSYS; >>>> + if (kvm_x86_ops->page_enc_status_hc) >>>> + ret = kvm_x86_ops->page_enc_status_hc(vcpu->kvm, >>>> + a0, a1, a2); >>>> + break; >>>> default: >>>> ret = -KVM_ENOSYS; >>>> break; >>>> diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h >>>> index 8b86609849b9..847b83b75dc8 100644 >>>> --- a/include/uapi/linux/kvm_para.h >>>> +++ b/include/uapi/linux/kvm_para.h >>>> @@ -29,6 +29,7 @@ >>>> #define KVM_HC_CLOCK_PAIRING 9 >>>> #define KVM_HC_SEND_IPI 10 >>>> #define KVM_HC_SCHED_YIELD 11 >>>> +#define KVM_HC_PAGE_ENC_STATUS 12 >>>> /* >>>> * hypercalls use architecture specific
| |