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Date: Tue, 12 Oct 2021 19:20:41 -0700
From: Krish Sadhukhan <krish.sadhukhan@...cle.com>
To: Michael Roth <michael.roth@....com>,
linux-kselftest@...r.kernel.org
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
Nathan Tempelman <natet@...gle.com>,
Marc Orr <marcorr@...gle.com>,
Steve Rutherford <srutherford@...gle.com>,
Sean Christopherson <seanjc@...gle.com>,
Mingwei Zhang <mizhang@...gle.com>,
Brijesh Singh <brijesh.singh@....com>,
Tom Lendacky <thomas.lendacky@....com>,
Varad Gautam <varad.gautam@...e.com>,
Shuah Khan <shuah@...nel.org>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
David Woodhouse <dwmw@...zon.co.uk>,
Ricardo Koller <ricarkol@...gle.com>,
Jim Mattson <jmattson@...gle.com>,
Wanpeng Li <wanpengli@...cent.com>,
Joerg Roedel <joro@...tes.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H . Peter Anvin" <hpa@...or.com>
Subject: Re: [RFC 02/16] KVM: selftests: add hooks for managing encrypted
guest memory
On 10/5/21 4:44 PM, Michael Roth wrote:
> VM implementations that make use of encrypted memory need a way to
> configure things like the encryption/shared bit position for page
> table handling, the default encryption policy for internal allocations
> made by the core library, and a way to fetch the list/bitmap of
> encrypted pages to do the actual memory encryption. Add an interface to
> configure these parameters. Also introduce a sparsebit map to track
> allocations/mappings that should be treated as encrypted, and provide
> a way for VM implementations to retrieve it to handle operations
> related memory encryption.
>
> Signed-off-by: Michael Roth <michael.roth@....com>
> ---
> .../testing/selftests/kvm/include/kvm_util.h | 6 ++
> tools/testing/selftests/kvm/lib/kvm_util.c | 63 +++++++++++++++++--
> .../selftests/kvm/lib/kvm_util_internal.h | 10 +++
> 3 files changed, 75 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 010b59b13917..f417de80596c 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -348,6 +348,12 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);
>
> void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid);
>
> +void vm_set_memory_encryption(struct kvm_vm *vm, bool enc_by_default, bool has_enc_bit,
> + uint8_t enc_bit);
> +struct sparsebit *vm_get_encrypted_phy_pages(struct kvm_vm *vm, int slot,
> + vm_paddr_t *gpa_start,
> + uint64_t *size);
> +
> /* Common ucalls */
> enum {
> UCALL_NONE,
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 92f59adddebe..c58f930dedd2 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -631,6 +631,7 @@ static void __vm_mem_region_delete(struct kvm_vm *vm,
> "rc: %i errno: %i", ret, errno);
>
> sparsebit_free(®ion->unused_phy_pages);
> + sparsebit_free(®ion->encrypted_phy_pages);
> ret = munmap(region->mmap_start, region->mmap_size);
> TEST_ASSERT(ret == 0, "munmap failed, rc: %i errno: %i", ret, errno);
>
> @@ -924,6 +925,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> }
>
> region->unused_phy_pages = sparsebit_alloc();
> + region->encrypted_phy_pages = sparsebit_alloc();
> sparsebit_set_num(region->unused_phy_pages,
> guest_paddr >> vm->page_shift, npages);
> region->region.slot = slot;
> @@ -1153,6 +1155,7 @@ void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid)
> * num - number of pages
> * paddr_min - Physical address minimum
> * memslot - Memory region to allocate page from
> + * encrypt - Whether to treat the pages as encrypted
> *
> * Output Args: None
> *
> @@ -1164,11 +1167,13 @@ void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid)
> * and their base address is returned. A TEST_ASSERT failure occurs if
> * not enough pages are available at or above paddr_min.
> */
> -vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
> - vm_paddr_t paddr_min, uint32_t memslot)
> +static vm_paddr_t
> +_vm_phy_pages_alloc(struct kvm_vm *vm, size_t num, vm_paddr_t paddr_min,
> + uint32_t memslot, bool encrypt)
> {
> struct userspace_mem_region *region;
> sparsebit_idx_t pg, base;
> + vm_paddr_t gpa;
>
> TEST_ASSERT(num > 0, "Must allocate at least one page");
>
> @@ -1198,10 +1203,25 @@ vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
> abort();
> }
>
> - for (pg = base; pg < base + num; ++pg)
> + for (pg = base; pg < base + num; ++pg) {
> sparsebit_clear(region->unused_phy_pages, pg);
> + if (encrypt)
> + sparsebit_set(region->encrypted_phy_pages, pg);
> + }
> +
> + gpa = base * vm->page_size;
>
> - return base * vm->page_size;
> + if (encrypt && vm->memcrypt.has_enc_bit)
> + gpa |= (1ULL << vm->memcrypt.enc_bit);
> +
> + return gpa;
> +}
> +
> +vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
> + vm_paddr_t paddr_min, uint32_t memslot)
> +{
> + return _vm_phy_pages_alloc(vm, 1, paddr_min, memslot,
> + vm->memcrypt.enc_by_default);
> }
>
> vm_paddr_t vm_phy_page_alloc(struct kvm_vm *vm, vm_paddr_t paddr_min,
> @@ -2146,6 +2166,10 @@ void vm_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
> region->host_mem);
> fprintf(stream, "%*sunused_phy_pages: ", indent + 2, "");
> sparsebit_dump(stream, region->unused_phy_pages, 0);
> + if (vm->memcrypt.enabled) {
> + fprintf(stream, "%*sencrypted_phy_pages: ", indent + 2, "");
> + sparsebit_dump(stream, region->encrypted_phy_pages, 0);
> + }
> }
> fprintf(stream, "%*sMapped Virtual Pages:\n", indent, "");
> sparsebit_dump(stream, vm->vpages_mapped, indent + 2);
> @@ -2343,3 +2367,34 @@ int vcpu_get_stats_fd(struct kvm_vm *vm, uint32_t vcpuid)
>
> return ioctl(vcpu->fd, KVM_GET_STATS_FD, NULL);
> }
> +
> +void vm_set_memory_encryption(struct kvm_vm *vm, bool enc_by_default, bool has_enc_bit,
> + uint8_t enc_bit)
> +{
> + vm->memcrypt.enabled = true;
> + vm->memcrypt.enc_by_default = enc_by_default;
> + vm->memcrypt.has_enc_bit = has_enc_bit;
> + vm->memcrypt.enc_bit = enc_bit;
> +}
> +
> +struct sparsebit *
> +vm_get_encrypted_phy_pages(struct kvm_vm *vm, int slot, vm_paddr_t *gpa_start,
> + uint64_t *size)
> +{
> + struct userspace_mem_region *region;
> + struct sparsebit *encrypted_phy_pages;
> +
> + if (!vm->memcrypt.enabled)
> + return NULL;
> +
> + region = memslot2region(vm, slot);
> + if (!region)
> + return NULL;
> +
> + encrypted_phy_pages = sparsebit_alloc();
> + sparsebit_copy(encrypted_phy_pages, region->encrypted_phy_pages);
> + *size = region->region.memory_size;
> + *gpa_start = region->region.guest_phys_addr;
> +
> + return encrypted_phy_pages;
> +}
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util_internal.h b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
> index a03febc24ba6..99ccab86115c 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util_internal.h
> +++ b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
> @@ -16,6 +16,7 @@
> struct userspace_mem_region {
> struct kvm_userspace_memory_region region;
> struct sparsebit *unused_phy_pages;
> + struct sparsebit *encrypted_phy_pages;
> int fd;
> off_t offset;
> void *host_mem;
> @@ -44,6 +45,14 @@ struct userspace_mem_regions {
> DECLARE_HASHTABLE(slot_hash, 9);
> };
>
> +/* Memory encryption policy/configuration. */
> +struct vm_memcrypt {
> + bool enabled;
> + int8_t enc_by_default;
> + bool has_enc_bit;
> + int8_t enc_bit;
> +};
> +
> struct kvm_vm {
> int mode;
> unsigned long type;
> @@ -67,6 +76,7 @@ struct kvm_vm {
> vm_vaddr_t idt;
> vm_vaddr_t handlers;
> uint32_t dirty_ring_size;
> + struct vm_memcrypt memcrypt;
For readability, it's probably better to adopt a standard naming
convention for structures, members and functions ? For example,
encrypted_phy_pages -> enc_phy_pages
struct vm_memcrypt { -> struct vm_mem_enc {
struct vm_memcrypt memcrypt -> struct vm_mem_enc mem_enc
vm_get_encrypted_phy_pages() -> vm_get_enc_phy_pages
> };
>
> struct vcpu *vcpu_find(struct kvm_vm *vm, uint32_t vcpuid);
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