Messages in this thread Patch in this message | | | From | Borislav Petkov <> | Subject | [PATCH -v2 03/11] virt/coco/sev-guest: Simplify extended guest request handling | Date | Tue, 21 Feb 2023 12:34:20 +0100 |
| |
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Return a specific error code - -ENOSPC - to signal the too small cert data buffer instead of checking exit code and exitinfo2.
While at it, hoist the *fw_err assignment in snp_issue_guest_request() so that a proper error value is returned to the callers.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> --- arch/x86/kernel/sev.c | 11 +++--- drivers/virt/coco/sev-guest/sev-guest.c | 46 ++++++++++++++----------- 2 files changed, 31 insertions(+), 26 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index c644c34372e8..6a3e1425ba17 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2209,15 +2209,16 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned if (ret) goto e_put; + *fw_err = ghcb->save.sw_exit_info_2; if (ghcb->save.sw_exit_info_2) { /* Number of expected pages are returned in RBX */ if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST && - ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN) + ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN) { input->data_npages = ghcb_get_rbx(ghcb); - - *fw_err = ghcb->save.sw_exit_info_2; - - ret = -EIO; + ret = -ENOSPC; + } else { + ret = -EIO; + } } e_put: diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index edaf6031c6d9..5b4cddf44a3a 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -322,7 +322,8 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in u8 type, void *req_buf, size_t req_sz, void *resp_buf, u32 resp_sz, __u64 *fw_err) { - unsigned long err; + unsigned long err, override_err = 0; + unsigned int override_npages = 0; u64 seqno; int rc; @@ -338,6 +339,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in if (rc) return rc; +retry_request: /* * Call firmware to process the request. In this function the encrypted * message enters shared memory with the host. So after this call the @@ -346,17 +348,24 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in */ rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); - /* - * If the extended guest request fails due to having too small of a - * certificate data buffer, retry the same guest request without the - * extended data request in order to increment the sequence number - * and thus avoid IV reuse. - */ - if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST && - err == SNP_GUEST_REQ_INVALID_LEN) { - const unsigned int certs_npages = snp_dev->input.data_npages; + switch (rc) { + case -ENOSPC: + /* + * If the extended guest request fails due to having too + * small of a certificate data buffer, retry the same + * guest request without the extended data request in + * order to increment the sequence number and thus avoid + * IV reuse. + */ + override_npages = snp_dev->input.data_npages; + exit_code = SVM_VMGEXIT_GUEST_REQUEST; - exit_code = SVM_VMGEXIT_GUEST_REQUEST; + /* + * Override the error to inform callers the given extended + * request buffer size was too small and give the caller the + * required buffer size. + */ + override_err = SNP_GUEST_REQ_INVALID_LEN; /* * If this call to the firmware succeeds, the sequence number can @@ -366,19 +375,14 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in * of the VMPCK and the error code being propagated back to the * user as an ioctl() return code. */ - rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); - - /* - * Override the error to inform callers the given extended - * request buffer size was too small and give the caller the - * required buffer size. - */ - err = SNP_GUEST_REQ_INVALID_LEN; - snp_dev->input.data_npages = certs_npages; + goto retry_request; } if (fw_err) - *fw_err = err; + *fw_err = override_err ?: err; + + if (override_npages) + snp_dev->input.data_npages = override_npages; if (rc) { dev_alert(snp_dev->dev, -- 2.35.1
| |