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Message-ID: <20211013150719.mnde2lw6ffks7pm4@amd.com>
Date: Wed, 13 Oct 2021 10:07:19 -0500
From: Michael Roth <michael.roth@....com>
To: Krish Sadhukhan <krish.sadhukhan@...cle.com>
CC: <linux-kselftest@...r.kernel.org>, <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 Tue, Oct 12, 2021 at 07:20:41PM -0700, Krish Sadhukhan wrote:
>
> 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
>
>
>
Makes sense, I will use this naming convention for the next spin.
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