From c688bd5dc94ee2677f820e4a566fbe98018847ff Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Fri, 1 Oct 2021 11:41:05 +0200 Subject: x86/sev: Carve out HV call's return value verification Carve out the verification of the HV call return value into a separate helper and make it more readable. No functional changes. Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/YVbYWz%2B8J7iMTJjc@zn.tnic --- arch/x86/kernel/sev-shared.c | 53 ++++++++++++++++++++++++-------------------- 1 file changed, 29 insertions(+), 24 deletions(-) (limited to 'arch/x86/kernel/sev-shared.c') diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index bf1033a62e48..4579c38a11c4 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -94,25 +94,15 @@ static void vc_finish_insn(struct es_em_ctxt *ctxt) ctxt->regs->ip += ctxt->insn.length; } -static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, - struct es_em_ctxt *ctxt, - u64 exit_code, u64 exit_info_1, - u64 exit_info_2) +static enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { - enum es_result ret; + u32 ret; - /* Fill in protocol and format specifiers */ - ghcb->protocol_version = GHCB_PROTOCOL_MAX; - ghcb->ghcb_usage = GHCB_DEFAULT_USAGE; + ret = ghcb->save.sw_exit_info_1 & GENMASK_ULL(31, 0); + if (!ret) + return ES_OK; - ghcb_set_sw_exit_code(ghcb, exit_code); - ghcb_set_sw_exit_info_1(ghcb, exit_info_1); - ghcb_set_sw_exit_info_2(ghcb, exit_info_2); - - sev_es_wr_ghcb_msr(__pa(ghcb)); - VMGEXIT(); - - if ((ghcb->save.sw_exit_info_1 & 0xffffffff) == 1) { + if (ret == 1) { u64 info = ghcb->save.sw_exit_info_2; unsigned long v; @@ -124,19 +114,34 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, ((v == X86_TRAP_GP) || (v == X86_TRAP_UD)) && ((info & SVM_EVTINJ_TYPE_MASK) == SVM_EVTINJ_TYPE_EXEPT)) { ctxt->fi.vector = v; + if (info & SVM_EVTINJ_VALID_ERR) ctxt->fi.error_code = info >> 32; - ret = ES_EXCEPTION; - } else { - ret = ES_VMM_ERROR; + + return ES_EXCEPTION; } - } else if (ghcb->save.sw_exit_info_1 & 0xffffffff) { - ret = ES_VMM_ERROR; - } else { - ret = ES_OK; } - return ret; + return ES_VMM_ERROR; +} + +static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, + struct es_em_ctxt *ctxt, + u64 exit_code, u64 exit_info_1, + u64 exit_info_2) +{ + /* Fill in protocol and format specifiers */ + ghcb->protocol_version = GHCB_PROTOCOL_MAX; + ghcb->ghcb_usage = GHCB_DEFAULT_USAGE; + + ghcb_set_sw_exit_code(ghcb, exit_code); + ghcb_set_sw_exit_info_1(ghcb, exit_info_1); + ghcb_set_sw_exit_info_2(ghcb, exit_info_2); + + sev_es_wr_ghcb_msr(__pa(ghcb)); + VMGEXIT(); + + return verify_exception_info(ghcb, ctxt); } /* -- cgit From 007faec014cb5d26983c1f86fd08c6539b41392e Mon Sep 17 00:00:00 2001 From: Tianyu Lan Date: Mon, 25 Oct 2021 08:21:10 -0400 Subject: x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV 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 Signed-off-by: Borislav Petkov Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20211025122116.264793-6-ltykernel@gmail.com --- arch/x86/kernel/sev-shared.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) (limited to 'arch/x86/kernel/sev-shared.c') diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 4579c38a11c4..0aacd6047ef2 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -125,10 +125,9 @@ static enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt return ES_VMM_ERROR; } -static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, - struct es_em_ctxt *ctxt, - u64 exit_code, u64 exit_info_1, - u64 exit_info_2) +enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, bool set_ghcb_msr, + struct es_em_ctxt *ctxt, u64 exit_code, + u64 exit_info_1, u64 exit_info_2) { /* Fill in protocol and format specifiers */ ghcb->protocol_version = GHCB_PROTOCOL_MAX; @@ -138,7 +137,14 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, ghcb_set_sw_exit_info_1(ghcb, exit_info_1); ghcb_set_sw_exit_info_2(ghcb, exit_info_2); - sev_es_wr_ghcb_msr(__pa(ghcb)); + /* + * Hyper-V unenlightened guests use a paravisor for communicating and + * GHCB pages are being allocated and set up by that paravisor. Linux + * should not change the GHCB page's physical address. + */ + if (set_ghcb_msr) + sev_es_wr_ghcb_msr(__pa(ghcb)); + VMGEXIT(); return verify_exception_info(ghcb, ctxt); @@ -418,7 +424,7 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) */ sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer); ghcb_set_sw_scratch(ghcb, sw_scratch); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_IOIO, exit_info_1, exit_info_2); if (ret != ES_OK) return ret; @@ -460,7 +466,8 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) ghcb_set_rax(ghcb, rax); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, + SVM_EXIT_IOIO, exit_info_1, 0); if (ret != ES_OK) return ret; @@ -491,7 +498,7 @@ static enum es_result vc_handle_cpuid(struct ghcb *ghcb, /* xgetbv will cause #GP - use reset value for xcr0 */ ghcb_set_xcr0(ghcb, 1); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_CPUID, 0, 0); if (ret != ES_OK) return ret; @@ -516,7 +523,7 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); enum es_result ret; - ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, exit_code, 0, 0); if (ret != ES_OK) return ret; -- cgit