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KVM: SVM: Add support for SEV DEBUG_ENCRYPT command 

The command copies a plaintext into guest memory and encrypts it using
the VM encryption key. The command will be used for debug purposes
(e.g setting breakpoints through gdbserver)

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>
This commit is contained in:
Brijesh Singh 2017-12-04 10:57:37 -06:00
parent 24f41fb23a
commit 7d1594f5d9
1 changed files with 93 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
arch/x86/kvm/svm.c
View File

@ -6240,6 +6240,83 @@ static int __sev_dbg_decrypt_user(struct kvm *kvm, unsigned long paddr,
return ret;
}
static int __sev_dbg_encrypt_user(struct kvm *kvm, unsigned long paddr,
unsigned long __user vaddr,
unsigned long dst_paddr,
unsigned long __user dst_vaddr,
int size, int *error)
{
struct page *src_tpage = NULL;
struct page *dst_tpage = NULL;
int ret, len = size;
/* If source buffer is not aligned then use an intermediate buffer */
if (!IS_ALIGNED(vaddr, 16)) {
src_tpage = alloc_page(GFP_KERNEL);
if (!src_tpage)
return -ENOMEM;
if (copy_from_user(page_address(src_tpage),
(void __user *)(uintptr_t)vaddr, size)) {
__free_page(src_tpage);
return -EFAULT;
}
paddr = __sme_page_pa(src_tpage);
}
/*
* If destination buffer or length is not aligned then do read-modify-write:
* - decrypt destination in an intermediate buffer
* - copy the source buffer in an intermediate buffer
* - use the intermediate buffer as source buffer
*/
if (!IS_ALIGNED(dst_vaddr, 16) || !IS_ALIGNED(size, 16)) {
int dst_offset;
dst_tpage = alloc_page(GFP_KERNEL);
if (!dst_tpage) {
ret = -ENOMEM;
goto e_free;
}
ret = __sev_dbg_decrypt(kvm, dst_paddr,
__sme_page_pa(dst_tpage), size, error);
if (ret)
goto e_free;
/*
* If source is kernel buffer then use memcpy() otherwise
* copy_from_user().
*/
dst_offset = dst_paddr & 15;
if (src_tpage)
memcpy(page_address(dst_tpage) + dst_offset,
page_address(src_tpage), size);
else {
if (copy_from_user(page_address(dst_tpage) + dst_offset,
(void __user *)(uintptr_t)vaddr, size)) {
ret = -EFAULT;
goto e_free;
}
}
paddr = __sme_page_pa(dst_tpage);
dst_paddr = round_down(dst_paddr, 16);
len = round_up(size, 16);
}
ret = __sev_issue_dbg_cmd(kvm, paddr, dst_paddr, len, error, true);
e_free:
if (src_tpage)
__free_page(src_tpage);
if (dst_tpage)
__free_page(dst_tpage);
return ret;
}
static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
{
unsigned long vaddr, vaddr_end, next_vaddr;
@ -6292,11 +6369,19 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
d_off = dst_vaddr & ~PAGE_MASK;
len = min_t(size_t, (PAGE_SIZE - s_off), size);
ret = __sev_dbg_decrypt_user(kvm,
__sme_page_pa(src_p[0]) + s_off,
dst_vaddr,
__sme_page_pa(dst_p[0]) + d_off,
len, &argp->error);
if (dec)
ret = __sev_dbg_decrypt_user(kvm,
__sme_page_pa(src_p[0]) + s_off,
dst_vaddr,
__sme_page_pa(dst_p[0]) + d_off,
len, &argp->error);
else
ret = __sev_dbg_encrypt_user(kvm,
__sme_page_pa(src_p[0]) + s_off,
vaddr,
__sme_page_pa(dst_p[0]) + d_off,
dst_vaddr,
len, &argp->error);
sev_unpin_memory(kvm, src_p, 1);
sev_unpin_memory(kvm, dst_p, 1);
@ -6347,6 +6432,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
case KVM_SEV_DBG_DECRYPT:
r = sev_dbg_crypt(kvm, &sev_cmd, true);
break;
case KVM_SEV_DBG_ENCRYPT:
r = sev_dbg_crypt(kvm, &sev_cmd, false);
break;
default:
r = -EINVAL;
goto out;