* [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary
@ 2018-04-07 23:03 Boris Ostrovsky
2018-04-09 7:06 ` Juergen Gross
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Boris Ostrovsky @ 2018-04-07 23:03 UTC (permalink / raw)
To: xen-devel
Cc: jgross, sstabellini, wei.liu2, George.Dunlap, andrew.cooper3,
ian.jackson, tim, julien.grall, jbeulich, Boris Ostrovsky
Commit 4a5733771e6f ("libxl: put RSDP for PVH guest near 4GB") breaks
pre-4.17 Linux guests since they do not use start_info's rsdp_paddr
pointer and instread scan BIOS memory for RSDP signature.
Introduce XENFEAT_rsdp_unrestricted feature flag that indicates whether
the guest can handle RSDP at locations pointed to by rsdp_paddr.
Since only Linux PVH guests suffer from this problem (BSD has always
relied on rsdp_paddr) we check this flag just for those guests. If the
flag is not set we place RSDP in BIOS, as before.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
tools/libxl/libxl_x86_acpi.c | 13 +++++++++++--
xen/include/public/features.h | 8 ++++++++
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/tools/libxl/libxl_x86_acpi.c b/tools/libxl/libxl_x86_acpi.c
index fe87418bc1..046d4866c7 100644
--- a/tools/libxl/libxl_x86_acpi.c
+++ b/tools/libxl/libxl_x86_acpi.c
@@ -218,8 +218,17 @@ int libxl__dom_load_acpi(libxl__gc *gc,
dom->acpi_modules[0].data = (void *)config.rsdp;
dom->acpi_modules[0].length = 64;
- dom->acpi_modules[0].guest_addr_out = ACPI_INFO_PHYSICAL_ADDRESS +
- (1 + acpi_pages_num) * libxl_ctxt.page_size;
+ /*
+ * Some Linux versions cannot properly process hvm_start_info.rsdp_paddr
+ * and so we need to put RSDP in location that can be discovered by ACPI's
+ * standard search method, in R-O BIOS memory (we chose last 64 bytes)
+ */
+ if (strcmp(dom->parms.guest_os, "linux") ||
+ elf_xen_feature_get(XENFEAT_rsdp_unrestricted, dom->parms.f_supported))
+ dom->acpi_modules[0].guest_addr_out = ACPI_INFO_PHYSICAL_ADDRESS +
+ (1 + acpi_pages_num) * libxl_ctxt.page_size;
+ else
+ dom->acpi_modules[0].guest_addr_out = 0x100000 - 64;
dom->acpi_modules[1].data = (void *)config.infop;
dom->acpi_modules[1].length = 4096;
diff --git a/xen/include/public/features.h b/xen/include/public/features.h
index 1a989b8bf9..c5319fbfbf 100644
--- a/xen/include/public/features.h
+++ b/xen/include/public/features.h
@@ -105,6 +105,14 @@
/* arm: Hypervisor supports ARM SMC calling convention. */
#define XENFEAT_ARM_SMCCC_supported 14
+/*
+ * x86/PVH: If set, ACPI RSDP can be placed at any address. Otherwise RSDP
+ * must be located in lower 1MB, as required by ACPI Specification for IA-PC
+ * systems.
+ * This feature flag is only consulted for Linux guests.
+ */
+#define XENFEAT_rsdp_unrestricted 15
+
#define XENFEAT_NR_SUBMAPS 1
#endif /* __XEN_PUBLIC_FEATURES_H__ */
--
2.14.3
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^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary
2018-04-07 23:03 [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary Boris Ostrovsky
@ 2018-04-09 7:06 ` Juergen Gross
2018-04-09 9:06 ` Roger Pau Monné
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Juergen Gross @ 2018-04-09 7:06 UTC (permalink / raw)
To: Boris Ostrovsky, xen-devel
Cc: sstabellini, wei.liu2, George.Dunlap, andrew.cooper3,
ian.jackson, tim, julien.grall, jbeulich
On 08/04/18 01:03, Boris Ostrovsky wrote:
> Commit 4a5733771e6f ("libxl: put RSDP for PVH guest near 4GB") breaks
> pre-4.17 Linux guests since they do not use start_info's rsdp_paddr
> pointer and instread scan BIOS memory for RSDP signature.
>
> Introduce XENFEAT_rsdp_unrestricted feature flag that indicates whether
> the guest can handle RSDP at locations pointed to by rsdp_paddr.
>
> Since only Linux PVH guests suffer from this problem (BSD has always
> relied on rsdp_paddr) we check this flag just for those guests. If the
> flag is not set we place RSDP in BIOS, as before.
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Juergen
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary
2018-04-07 23:03 [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary Boris Ostrovsky
2018-04-09 7:06 ` Juergen Gross
@ 2018-04-09 9:06 ` Roger Pau Monné
2018-04-09 9:20 ` Wei Liu
2018-04-09 10:03 ` George Dunlap
3 siblings, 0 replies; 5+ messages in thread
From: Roger Pau Monné @ 2018-04-09 9:06 UTC (permalink / raw)
To: Boris Ostrovsky
Cc: jgross, sstabellini, wei.liu2, George.Dunlap, andrew.cooper3,
ian.jackson, tim, julien.grall, jbeulich, xen-devel
On Sat, Apr 07, 2018 at 07:03:32PM -0400, Boris Ostrovsky wrote:
> Commit 4a5733771e6f ("libxl: put RSDP for PVH guest near 4GB") breaks
> pre-4.17 Linux guests since they do not use start_info's rsdp_paddr
> pointer and instread scan BIOS memory for RSDP signature.
>
> Introduce XENFEAT_rsdp_unrestricted feature flag that indicates whether
> the guest can handle RSDP at locations pointed to by rsdp_paddr.
>
> Since only Linux PVH guests suffer from this problem (BSD has always
> relied on rsdp_paddr) we check this flag just for those guests. If the
> flag is not set we place RSDP in BIOS, as before.
LGTM if we agree to do this based on the contents of
XEN_ELFNOTE_GUEST_OS. I think this is the first time we have a feature
flag that depends on the OS type.
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
> tools/libxl/libxl_x86_acpi.c | 13 +++++++++++--
> xen/include/public/features.h | 8 ++++++++
> 2 files changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/tools/libxl/libxl_x86_acpi.c b/tools/libxl/libxl_x86_acpi.c
> index fe87418bc1..046d4866c7 100644
> --- a/tools/libxl/libxl_x86_acpi.c
> +++ b/tools/libxl/libxl_x86_acpi.c
> @@ -218,8 +218,17 @@ int libxl__dom_load_acpi(libxl__gc *gc,
>
> dom->acpi_modules[0].data = (void *)config.rsdp;
> dom->acpi_modules[0].length = 64;
> - dom->acpi_modules[0].guest_addr_out = ACPI_INFO_PHYSICAL_ADDRESS +
> - (1 + acpi_pages_num) * libxl_ctxt.page_size;
> + /*
> + * Some Linux versions cannot properly process hvm_start_info.rsdp_paddr
> + * and so we need to put RSDP in location that can be discovered by ACPI's
> + * standard search method, in R-O BIOS memory (we chose last 64 bytes)
> + */
> + if (strcmp(dom->parms.guest_os, "linux") ||
> + elf_xen_feature_get(XENFEAT_rsdp_unrestricted, dom->parms.f_supported))
> + dom->acpi_modules[0].guest_addr_out = ACPI_INFO_PHYSICAL_ADDRESS +
> + (1 + acpi_pages_num) * libxl_ctxt.page_size;
> + else
> + dom->acpi_modules[0].guest_addr_out = 0x100000 - 64;
>
> dom->acpi_modules[1].data = (void *)config.infop;
> dom->acpi_modules[1].length = 4096;
> diff --git a/xen/include/public/features.h b/xen/include/public/features.h
> index 1a989b8bf9..c5319fbfbf 100644
> --- a/xen/include/public/features.h
> +++ b/xen/include/public/features.h
> @@ -105,6 +105,14 @@
> /* arm: Hypervisor supports ARM SMC calling convention. */
> #define XENFEAT_ARM_SMCCC_supported 14
>
> +/*
> + * x86/PVH: If set, ACPI RSDP can be placed at any address. Otherwise RSDP
> + * must be located in lower 1MB, as required by ACPI Specification for IA-PC
> + * systems.
> + * This feature flag is only consulted for Linux guests.
I would slightly change the above to be more explicit:
This feature flag is only consulted if XEN_ELFNOTE_GUEST_OS contains
the "linux" string.
Thanks, Roger.
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary
2018-04-07 23:03 [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary Boris Ostrovsky
2018-04-09 7:06 ` Juergen Gross
2018-04-09 9:06 ` Roger Pau Monné
@ 2018-04-09 9:20 ` Wei Liu
2018-04-09 10:03 ` George Dunlap
3 siblings, 0 replies; 5+ messages in thread
From: Wei Liu @ 2018-04-09 9:20 UTC (permalink / raw)
To: Boris Ostrovsky
Cc: jgross, sstabellini, wei.liu2, George.Dunlap, andrew.cooper3,
ian.jackson, tim, julien.grall, jbeulich, xen-devel
On Sat, Apr 07, 2018 at 07:03:32PM -0400, Boris Ostrovsky wrote:
> Commit 4a5733771e6f ("libxl: put RSDP for PVH guest near 4GB") breaks
> pre-4.17 Linux guests since they do not use start_info's rsdp_paddr
> pointer and instread scan BIOS memory for RSDP signature.
>
> Introduce XENFEAT_rsdp_unrestricted feature flag that indicates whether
> the guest can handle RSDP at locations pointed to by rsdp_paddr.
>
> Since only Linux PVH guests suffer from this problem (BSD has always
> relied on rsdp_paddr) we check this flag just for those guests. If the
> flag is not set we place RSDP in BIOS, as before.
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
> tools/libxl/libxl_x86_acpi.c | 13 +++++++++++--
> xen/include/public/features.h | 8 ++++++++
> 2 files changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/tools/libxl/libxl_x86_acpi.c b/tools/libxl/libxl_x86_acpi.c
> index fe87418bc1..046d4866c7 100644
> --- a/tools/libxl/libxl_x86_acpi.c
> +++ b/tools/libxl/libxl_x86_acpi.c
> @@ -218,8 +218,17 @@ int libxl__dom_load_acpi(libxl__gc *gc,
>
> dom->acpi_modules[0].data = (void *)config.rsdp;
> dom->acpi_modules[0].length = 64;
> - dom->acpi_modules[0].guest_addr_out = ACPI_INFO_PHYSICAL_ADDRESS +
> - (1 + acpi_pages_num) * libxl_ctxt.page_size;
> + /*
> + * Some Linux versions cannot properly process hvm_start_info.rsdp_paddr
> + * and so we need to put RSDP in location that can be discovered by ACPI's
> + * standard search method, in R-O BIOS memory (we chose last 64 bytes)
> + */
> + if (strcmp(dom->parms.guest_os, "linux") ||
> + elf_xen_feature_get(XENFEAT_rsdp_unrestricted, dom->parms.f_supported))
> + dom->acpi_modules[0].guest_addr_out = ACPI_INFO_PHYSICAL_ADDRESS +
> + (1 + acpi_pages_num) * libxl_ctxt.page_size;
> + else
> + dom->acpi_modules[0].guest_addr_out = 0x100000 - 64;
>
> dom->acpi_modules[1].data = (void *)config.infop;
> dom->acpi_modules[1].length = 4096;
> diff --git a/xen/include/public/features.h b/xen/include/public/features.h
> index 1a989b8bf9..c5319fbfbf 100644
> --- a/xen/include/public/features.h
> +++ b/xen/include/public/features.h
> @@ -105,6 +105,14 @@
> /* arm: Hypervisor supports ARM SMC calling convention. */
> #define XENFEAT_ARM_SMCCC_supported 14
>
> +/*
> + * x86/PVH: If set, ACPI RSDP can be placed at any address. Otherwise RSDP
> + * must be located in lower 1MB, as required by ACPI Specification for IA-PC
> + * systems.
> + * This feature flag is only consulted for Linux guests.
> + */
> +#define XENFEAT_rsdp_unrestricted 15
> +
It seems that this flag will remain linux only forever? If so, why not
add _linux_ to the name to make it clear?
(I don't normally bikeshed names, but this is public interface which
could use a bit of bikeshedding)
Wei.
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary
2018-04-07 23:03 [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary Boris Ostrovsky
` (2 preceding siblings ...)
2018-04-09 9:20 ` Wei Liu
@ 2018-04-09 10:03 ` George Dunlap
3 siblings, 0 replies; 5+ messages in thread
From: George Dunlap @ 2018-04-09 10:03 UTC (permalink / raw)
To: Boris Ostrovsky, xen-devel
Cc: jgross, sstabellini, wei.liu2, George.Dunlap, andrew.cooper3,
ian.jackson, tim, julien.grall, jbeulich
On 04/08/2018 12:03 AM, Boris Ostrovsky wrote:
> Commit 4a5733771e6f ("libxl: put RSDP for PVH guest near 4GB") breaks
> pre-4.17 Linux guests since they do not use start_info's rsdp_paddr
> pointer and instread scan BIOS memory for RSDP signature.
>
> Introduce XENFEAT_rsdp_unrestricted feature flag that indicates whether
> the guest can handle RSDP at locations pointed to by rsdp_paddr.
>
> Since only Linux PVH guests suffer from this problem (BSD has always
> relied on rsdp_paddr) we check this flag just for those guests. If the
> flag is not set we place RSDP in BIOS, as before.
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Thanks guys:
Acked-by: George Dunlap <george.dunlap@citrix.com>
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2018-04-07 23:03 [PATCH] x86/PVH/libxl: Check whether Linux guest can handle RSDP at 4G boundary Boris Ostrovsky
2018-04-09 7:06 ` Juergen Gross
2018-04-09 9:06 ` Roger Pau Monné
2018-04-09 9:20 ` Wei Liu
2018-04-09 10:03 ` George Dunlap
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