On Wed, 10 Jul 2019, Singh, Brijesh wrote:
> diff --git a/Documentation/virtual/kvm/hypercalls.txt
> b/Documentation/virtual/kvm/hypercalls.txt
> index da24c138c8d1..94f0611f4d88 100644
> --- a/Documentation/virtual/kvm/hypercalls.txt
> +++ b/Documentation/virtual/kvm/hypercalls.txt
> @@ -141,3 +141,17 @@ a0 corresponds to the APIC ID in the third argument
> (a2), bit 1
> corresponds to the APIC ID a2+1, and so on.
>
> Returns the number of CPUs to which the IPIs were delivered successfully.
> +
> +7. 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 26d1eb83f72a..b463a81dc176 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1199,6 +1199,8 @@ struct kvm_x86_ops {
> uint16_t (*nested_get_evmcs_version)(struct kvm_vcpu *vcpu);
>
> bool (*need_emulation_on_page_fault)(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 3089942f6630..431718309359 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -135,6 +135,8 @@ 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 {
> @@ -1910,6 +1912,8 @@ static void sev_vm_destroy(struct kvm *kvm)
>
> sev_unbind_asid(kvm, sev->handle);
> sev_asid_free(kvm);
> +
> + kvfree(sev->page_enc_bmap);
> }
>
> static void avic_vm_destroy(struct kvm *kvm)
Adding Cfir who flagged this kvfree().
Other freeing of sev->page_enc_bmap in this patch also set
sev->page_enc_bmap_size to 0 and neither set sev->page_enc_bmap to NULL
after freeing it.
For extra safety, is it possible to sev->page_enc_bmap = NULL anytime the
bitmap is kvfreed?
> @@ -2084,6 +2088,7 @@ static void avic_set_running(struct kvm_vcpu *vcpu,
> bool is_run)
>
> static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> {
> + struct kvm_sev_info *sev = &to_kvm_svm(vcpu->kvm)->sev_info;
> struct vcpu_svm *svm = to_svm(vcpu);
> u32 dummy;
> u32 eax = 1;
> @@ -2105,6 +2110,12 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool
> init_event)
>
> if (kvm_vcpu_apicv_active(vcpu) && !init_event)
> avic_update_vapic_bar(svm, APIC_DEFAULT_PHYS_BASE);
> +
> + /* reset the page encryption bitmap */
> + if (sev_guest(vcpu->kvm)) {
> + kvfree(sev->page_enc_bmap);
> + sev->page_enc_bmap_size = 0;
> + }
> }
>
> static int avic_init_vcpu(struct vcpu_svm *svm)
What is protecting sev->page_enc_bmap and sev->page_enc_bmap_size in calls
to svm_vcpu_reset()?
