lkml.org 
[lkml]   [2022]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v8 2/4] x86/sev: Change snp_guest_issue_request's fw_err
From
On 11/4/22 18:00, Dionna Glaze wrote:
> The GHCB specification declares that the firmware error value for a
> guest request will be stored in the lower 32 bits of EXIT_INFO_2.
> The upper 32 bits are for the VMM's own error code. The fw_err argument
> is thus a misnomer, and callers will need access to all 64 bits.
>
> The type of unsigned long also causes problems, since sw_exit_info2 is
> u64 (unsigned long long) vs the argument's previous unsigned long*.
> The signature change requires the follow-up change to
> drivers/virt/coco/sev-guest to use the new expected type in order to
> compile.
>
> The firmware might not even be called, so we bookend the call with the
> no firmware call error and clearing the error.
>
> Cc: Tom Lendacky <Thomas.Lendacky@amd.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Joerg Roedel <jroedel@suse.de>
> Cc: Peter Gonda <pgonda@google.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Venu Busireddy <venu.busireddy@oracle.com>
> Cc: Michael Roth <michael.roth@amd.com>
> Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
> Cc: Michael Sterritt <sterritt@google.com>
>
> Fixes: d5af44dde546 ("x86/sev: Provide support for SNP guest request NAEs")
> Signed-off-by: Dionna Glaze <dionnaglaze@google.com>

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>

> ---
> arch/x86/include/asm/sev.h | 4 ++--
> arch/x86/kernel/sev.c | 10 ++++++----
> 2 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
> index ebc271bb6d8e..05de34d10d89 100644
> --- a/arch/x86/include/asm/sev.h
> +++ b/arch/x86/include/asm/sev.h
> @@ -196,7 +196,7 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages);
> void snp_set_wakeup_secondary_cpu(void);
> bool snp_init(struct boot_params *bp);
> void __init __noreturn snp_abort(void);
> -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err);
> +int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, u64 *exitinfo2);
> #else
> static inline void sev_es_ist_enter(struct pt_regs *regs) { }
> static inline void sev_es_ist_exit(void) { }
> @@ -217,7 +217,7 @@ static inline void snp_set_wakeup_secondary_cpu(void) { }
> static inline bool snp_init(struct boot_params *bp) { return false; }
> static inline void snp_abort(void) { }
> static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input,
> - unsigned long *fw_err)
> + u64 *exitinfo2)
> {
> return -ENOTTY;
> }
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index a428c62330d3..148f17cb07b5 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -22,6 +22,7 @@
> #include <linux/efi.h>
> #include <linux/platform_device.h>
> #include <linux/io.h>
> +#include <linux/psp-sev.h>
>
> #include <asm/cpu_entry_area.h>
> #include <asm/stacktrace.h>
> @@ -2175,7 +2176,7 @@ static int __init init_sev_config(char *str)
> }
> __setup("sev=", init_sev_config);
>
> -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err)
> +int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, u64 *exitinfo2)
> {
> struct ghcb_state state;
> struct es_em_ctxt ctxt;
> @@ -2186,9 +2187,11 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
> if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
> return -ENODEV;
>
> - if (!fw_err)
> + if (!exitinfo2)
> return -EINVAL;
>
> + *exitinfo2 = SEV_RET_NO_FW_CALL;
> +
> /*
> * __sev_get_ghcb() needs to run with IRQs disabled because it is using
> * a per-CPU GHCB.
> @@ -2212,14 +2215,13 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
> if (ret)
> goto e_put;
>
> + *exitinfo2 = 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)
> input->data_npages = ghcb_get_rbx(ghcb);
>
> - *fw_err = ghcb->save.sw_exit_info_2;
> -
> ret = -EIO;
> }
>

\
 
 \ /
  Last update: 2022-11-14 22:02    [W:0.123 / U:0.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site