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x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV

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Hyper-V needs to issue the GHCB HV call in order to read/write MSRs in
Isolation VMs. For that, expose sev_es_ghcb_hv_call().

The Hyper-V Isolation VMs are unenlightened guests and run a paravisor
at VMPL0 for communicating. GHCB pages are being allocated and set up
by that paravisor. Linux gets the GHCB page's physical address via
MSR_AMD64_SEV_ES_GHCB from the paravisor and should not change it.

Add a @set_ghcb_msr parameter to sev_es_ghcb_hv_call() to control
whether the function should set the GHCB's address prior to the call or
not and export that function for use by HyperV.

  [ bp: - Massage commit message
        - add a struct ghcb forward declaration to fix randconfig builds. ]

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20211025122116.264793-6-ltykernel@gmail.com
This commit is contained in:
Tianyu Lan
2021-10-25 08:21:10 -04:00
committed by Borislav Petkov
parent ce47d0c00f
commit 007faec014
3 changed files with 29 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/x86/kernel/sev.c
View File

@ -648,7 +648,8 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
ghcb_set_rdx(ghcb, regs->dx);
}
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0);
ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_MSR,
exit_info_1, 0);
if ((ret == ES_OK) && (!exit_info_1)) {
regs->ax = ghcb->save.rax;
@ -867,7 +868,7 @@ static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
ghcb_set_sw_scratch(ghcb, ghcb_pa + offsetof(struct ghcb, shared_buffer));
return sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, exit_info_1, exit_info_2);
return sev_es_ghcb_hv_call(ghcb, true, ctxt, exit_code, exit_info_1, exit_info_2);
}
static enum es_result vc_handle_mmio_twobyte_ops(struct ghcb *ghcb,
@ -1117,7 +1118,7 @@ static enum es_result vc_handle_dr7_write(struct ghcb *ghcb,
/* Using a value of 0 for ExitInfo1 means RAX holds the value */
ghcb_set_rax(ghcb, val);
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WRITE_DR7, 0, 0);
ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_WRITE_DR7, 0, 0);
if (ret != ES_OK)
return ret;
@ -1147,7 +1148,7 @@ static enum es_result vc_handle_dr7_read(struct ghcb *ghcb,
static enum es_result vc_handle_wbinvd(struct ghcb *ghcb,
struct es_em_ctxt *ctxt)
{
return sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WBINVD, 0, 0);
return sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_WBINVD, 0, 0);
}
static enum es_result vc_handle_rdpmc(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
@ -1156,7 +1157,7 @@ static enum es_result vc_handle_rdpmc(struct ghcb *ghcb, struct es_em_ctxt *ctxt
ghcb_set_rcx(ghcb, ctxt->regs->cx);
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_RDPMC, 0, 0);
ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_RDPMC, 0, 0);
if (ret != ES_OK)
return ret;
@ -1197,7 +1198,7 @@ static enum es_result vc_handle_vmmcall(struct ghcb *ghcb,
if (x86_platform.hyper.sev_es_hcall_prepare)
x86_platform.hyper.sev_es_hcall_prepare(ghcb, ctxt->regs);
ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_VMMCALL, 0, 0);
ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_VMMCALL, 0, 0);
if (ret != ES_OK)
return ret;