From: Tom Lendacky <[email protected]> Add code to handle #VC exceptions on DR7 register reads and writes. This is needed early because show_regs() reads DR7 to print it out.
Signed-off-by: Tom Lendacky <[email protected]> [ [email protected]: - Adapt to #VC handling framework - Support early usage ] Co-developed-by: Joerg Roedel <[email protected]> Signed-off-by: Joerg Roedel <[email protected]> --- arch/x86/kernel/sev-es.c | 87 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 83 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 163b8a7f98a4..7a9cdc660637 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -23,6 +23,8 @@ #include <asm/traps.h> #include <asm/svm.h> +#define DR7_RESET_VALUE 0x400 + /* For early boot hypervisor communication in SEV-ES enabled guests */ struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); @@ -31,6 +33,7 @@ struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); * cleared */ struct ghcb __initdata *boot_ghcb; +static DEFINE_PER_CPU(unsigned long, cached_dr7) = DR7_RESET_VALUE; struct ghcb_state { struct ghcb *ghcb; @@ -359,6 +362,21 @@ static long *vc_insn_get_reg(struct es_em_ctxt *ctxt) return reg_array + offset; } +static long *vc_insn_get_rm(struct es_em_ctxt *ctxt) +{ + long *reg_array; + int offset; + + reg_array = (long *)ctxt->regs; + offset = insn_get_modrm_rm_off(&ctxt->insn, ctxt->regs); + + if (offset < 0) + return NULL; + + offset /= sizeof(long); + + return reg_array + offset; +} static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt, unsigned int bytes, bool read) { @@ -587,13 +605,74 @@ static enum es_result vc_handle_mmio(struct ghcb *ghcb, return ret; } +static enum es_result vc_handle_dr7_write(struct ghcb *ghcb, + struct es_em_ctxt *ctxt, + bool early) +{ + long val, *reg = vc_insn_get_rm(ctxt); + enum es_result ret; + + if (!reg) + return ES_DECODE_FAILED; + + val = *reg; + + /* Upper 32 bits must be written as zeroes */ + if (val >> 32) { + ctxt->fi.vector = X86_TRAP_GP; + ctxt->fi.error_code = 0; + return ES_EXCEPTION; + } + + /* Clear out other reservered bits and set bit 10 */ + val = (val & 0xffff23ffL) | BIT(10); + + /* Early non-zero writes to DR7 are not supported */ + if (early && (val & ~DR7_RESET_VALUE)) + return ES_UNSUPPORTED; + + /* 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); + if (ret != ES_OK) + return ret; + + this_cpu_write(cached_dr7, *reg); + + return ES_OK; +} + +static enum es_result vc_handle_dr7_read(struct ghcb *ghcb, + struct es_em_ctxt *ctxt, + bool early) +{ + long *reg = vc_insn_get_rm(ctxt); + + if (!reg) + return ES_DECODE_FAILED; + + if (early) + *reg = DR7_RESET_VALUE; + else + *reg = this_cpu_read(cached_dr7); + + return ES_OK; +} + static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt, - struct ghcb *ghcb, - unsigned long exit_code) + struct ghcb *ghcb, + unsigned long exit_code, + bool early) { enum es_result result; switch (exit_code) { + case SVM_EXIT_READ_DR7: + result = vc_handle_dr7_read(ghcb, ctxt, early); + break; + case SVM_EXIT_WRITE_DR7: + result = vc_handle_dr7_write(ghcb, ctxt, early); + break; case SVM_EXIT_CPUID: result = vc_handle_cpuid(ghcb, ctxt); break; @@ -682,7 +761,7 @@ dotraplinkage void do_vmm_communication(struct pt_regs *regs, unsigned long exit result = vc_context_filter(regs, exit_code); if (result == ES_OK) - result = vc_handle_exitcode(&ctxt, ghcb, exit_code); + result = vc_handle_exitcode(&ctxt, ghcb, exit_code, false); sev_es_put_ghcb(&state); @@ -750,7 +829,7 @@ bool __init boot_vc_exception(struct pt_regs *regs) result = vc_init_em_ctxt(&ctxt, regs, exit_code); if (result == ES_OK) - result = vc_handle_exitcode(&ctxt, boot_ghcb, exit_code); + result = vc_handle_exitcode(&ctxt, boot_ghcb, exit_code, true); /* Done - now check the result */ switch (result) { -- 2.17.1 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
